diff --git a/lib/private/User/LazyUser.php b/lib/private/User/LazyUser.php
index 3ae6a557a2d..25ea950bf85 100644
--- a/lib/private/User/LazyUser.php
+++ b/lib/private/User/LazyUser.php
@@ -1,6 +1,7 @@
 <?php
 
 declare(strict_types=1);
+
 /**
  * SPDX-FileCopyrightText: 2022 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
@@ -8,6 +9,7 @@ declare(strict_types=1);
 
 namespace OC\User;
 
+use OCP\IImage;
 use OCP\IUser;
 use OCP\IUserManager;
 use OCP\UserInterface;
@@ -47,7 +49,7 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function getDisplayName() {
+	public function getDisplayName(): string {
 		if ($this->displayName) {
 			return $this->displayName;
 		}
@@ -56,7 +58,7 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function setDisplayName($displayName) {
+	public function setDisplayName($displayName): bool {
 		return $this->getUser()->setDisplayName($displayName);
 	}
 
@@ -76,12 +78,12 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function delete() {
+	public function delete(): bool {
 		return $this->getUser()->delete();
 	}
 
 	#[\Override]
-	public function setPassword($password, $recoveryPassword = null) {
+	public function setPassword($password, $recoveryPassword = null): bool {
 		return $this->getUser()->setPassword($password, $recoveryPassword);
 	}
 
@@ -96,12 +98,12 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function getHome() {
+	public function getHome(): string {
 		return $this->getUser()->getHome();
 	}
 
 	#[\Override]
-	public function getBackendClassName() {
+	public function getBackendClassName(): string {
 		return $this->getUser()->getBackendClassName();
 	}
 
@@ -136,17 +138,17 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function isEnabled() {
+	public function isEnabled(): bool {
 		return $this->getUser()->isEnabled();
 	}
 
 	#[\Override]
-	public function setEnabled(bool $enabled = true) {
-		return $this->getUser()->setEnabled($enabled);
+	public function setEnabled(bool $enabled = true): void {
+		$this->getUser()->setEnabled($enabled);
 	}
 
 	#[\Override]
-	public function getEMailAddress() {
+	public function getEMailAddress(): string {
 		return $this->getUser()->getEMailAddress();
 	}
 
@@ -161,17 +163,17 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function getAvatarImage($size) {
+	public function getAvatarImage($size): ?IImage {
 		return $this->getUser()->getAvatarImage($size);
 	}
 
 	#[\Override]
-	public function getCloudId() {
+	public function getCloudId(): string {
 		return $this->getUser()->getCloudId();
 	}
 
 	#[\Override]
-	public function setEMailAddress($mailAddress) {
+	public function setEMailAddress($mailAddress): void {
 		$this->getUser()->setEMailAddress($mailAddress);
 	}
 
@@ -186,7 +188,7 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function getQuota() {
+	public function getQuota(): string {
 		return $this->getUser()->getQuota();
 	}
 
@@ -196,7 +198,7 @@ class LazyUser implements IUser {
 	}
 
 	#[\Override]
-	public function setQuota($quota) {
+	public function setQuota($quota): void {
 		$this->getUser()->setQuota($quota);
 	}
 
diff --git a/lib/private/User/User.php b/lib/private/User/User.php
index d22b8ae89a4..e54ac397b3e 100644
--- a/lib/private/User/User.php
+++ b/lib/private/User/User.php
@@ -481,11 +481,9 @@ class User implements IUser {
 
 	/**
 	 * set the enabled status for the user
-	 *
-	 * @return void
 	 */
 	#[\Override]
-	public function setEnabled(bool $enabled = true) {
+	public function setEnabled(bool $enabled = true): void {
 		$oldStatus = $this->isEnabled();
 		$setDatabaseValue = function (bool $enabled): void {
 			$this->config->setUserValue($this->uid, 'core', 'enabled', $enabled ? 'true' : 'false');
@@ -524,18 +522,12 @@ class User implements IUser {
 		return $this->getPrimaryEMailAddress() ?? $this->getSystemEMailAddress();
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	#[\Override]
 	public function getSystemEMailAddress(): ?string {
 		$email = $this->config->getUserValue($this->uid, 'settings', 'email', null);
 		return $email ? mb_strtolower(trim($email)) : null;
 	}
 
-	/**
-	 * @inheritDoc
-	 */
 	#[\Override]
 	public function getPrimaryEMailAddress(): ?string {
 		$email = $this->config->getUserValue($this->uid, 'settings', 'primary_email', null);
diff --git a/lib/public/IUser.php b/lib/public/IUser.php
index 5a06577fde7..afbcfd2df08 100644
--- a/lib/public/IUser.php
+++ b/lib/public/IUser.php
@@ -27,36 +27,31 @@ interface IUser {
 	/**
 	 * get the user id
 	 *
-	 * @return string
 	 * @since 8.0.0
 	 */
-	public function getUID();
+	public function getUID(): string;
 
 	/**
 	 * get the display name for the user, if no specific display name is set it will fallback to the user id
 	 *
-	 * @return string
 	 * @since 8.0.0
 	 */
-	public function getDisplayName();
+	public function getDisplayName(): string;
 
 	/**
 	 * set the display name for the user
 	 *
-	 * @param string $displayName
-	 * @return bool
 	 * @since 8.0.0
 	 *
 	 * @since 25.0.0 Throw InvalidArgumentException
 	 * @throws \InvalidArgumentException
 	 */
-	public function setDisplayName($displayName);
+	public function setDisplayName(string $displayName): bool;
 
 	/**
 	 * returns the timestamp of the user's last login or 0 if the user did never
 	 * login
 	 *
-	 * @return int
 	 * @since 8.0.0
 	 */
 	public function getLastLogin(): int;
@@ -79,20 +74,18 @@ interface IUser {
 	/**
 	 * Delete the user
 	 *
-	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function delete();
+	public function delete(): bool;
 
 	/**
 	 * Set the password of the user
 	 *
 	 * @param string $password
 	 * @param string $recoveryPassword for the encryption app to reset encryption keys
-	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function setPassword($password, $recoveryPassword = null);
+	public function setPassword($password, $recoveryPassword = null): bool;
 
 	/**
 	 * Get the password hash of the user
@@ -114,25 +107,23 @@ interface IUser {
 	/**
 	 * get the users home folder to mount
 	 *
-	 * @return string
 	 * @since 8.0.0
 	 */
-	public function getHome();
+	public function getHome(): string;
 
 	/**
 	 * Get the name of the backend class the user is connected with
 	 *
-	 * @return string
 	 * @since 8.0.0
 	 */
-	public function getBackendClassName();
+	public function getBackendClassName(): string;
 
 	/**
 	 * Get the backend for the current user object
-	 * @return ?UserInterface
+	 *
 	 * @since 15.0.0
 	 */
-	public function getBackend();
+	public function getBackend(): ?UserInterface;
 
 	/**
 	 * check if the backend allows the user to change their avatar on Personal page
@@ -171,26 +162,23 @@ interface IUser {
 	/**
 	 * check if the user is enabled
 	 *
-	 * @return bool
 	 * @since 8.0.0
 	 */
-	public function isEnabled();
+	public function isEnabled(): bool;
 
 	/**
 	 * set the enabled status for the user
 	 *
-	 * @param bool $enabled
 	 * @since 8.0.0
 	 */
-	public function setEnabled(bool $enabled = true);
+	public function setEnabled(bool $enabled = true): void;
 
 	/**
 	 * get the user's email address
 	 *
-	 * @return string|null
 	 * @since 9.0.0
 	 */
-	public function getEMailAddress();
+	public function getEMailAddress(): ?string;
 
 	/**
 	 * get the user's system email address
@@ -201,7 +189,6 @@ interface IUser {
 	 * Use this getter only when the system address is needed. For picking the
 	 * proper address to e.g. send a mail to, use getEMailAddress().
 	 *
-	 * @return string|null
 	 * @since 23.0.0
 	 */
 	public function getSystemEMailAddress(): ?string;
@@ -216,7 +203,6 @@ interface IUser {
 	 * Use this getter only when the primary address is needed. For picking the
 	 * proper address to e.g. send a mail to, use getEMailAddress().
 	 *
-	 * @return string|null
 	 * @since 23.0.0
 	 */
 	public function getPrimaryEMailAddress(): ?string;
@@ -225,10 +211,9 @@ interface IUser {
 	 * get the avatar image if it exists
 	 *
 	 * @param int $size
-	 * @return IImage|null
 	 * @since 9.0.0
 	 */
-	public function getAvatarImage($size);
+	public function getAvatarImage($size): ?IImage;
 
 	/**
 	 * get the federation cloud id
@@ -244,11 +229,10 @@ interface IUser {
 	 * It is an alias to setSystemEMailAddress()
 	 *
 	 * @param string|null $mailAddress
-	 * @return void
 	 * @since 9.0.0
 	 * @deprecated 23.0.0 use setSystemEMailAddress() or setPrimaryEMailAddress()
 	 */
-	public function setEMailAddress($mailAddress);
+	public function setEMailAddress($mailAddress): void;
 
 	/**
 	 * Set the system email address of the user
@@ -282,10 +266,9 @@ interface IUser {
 	 * set for the user, the default value is returned. If a default setting
 	 * was not set otherwise, it is return as 'none', i.e. quota is not limited.
 	 *
-	 * @return string
 	 * @since 9.0.0
 	 */
-	public function getQuota();
+	public function getQuota(): string;
 
 	/**
 	 * Get the users' quota in machine readable form. If a specific quota is set
@@ -300,10 +283,9 @@ interface IUser {
 	 * set the users' quota
 	 *
 	 * @param string $quota
-	 * @return void
 	 * @since 9.0.0
 	 */
-	public function setQuota($quota);
+	public function setQuota($quota): void;
 
 	/**
 	 * Get the user's manager UIDs