diff --git a/apps/dav/lib/Connector/Sabre/TagsPlugin.php b/apps/dav/lib/Connector/Sabre/TagsPlugin.php
index 9f9c3be24c5ef..c92003a65415e 100644
--- a/apps/dav/lib/Connector/Sabre/TagsPlugin.php
+++ b/apps/dav/lib/Connector/Sabre/TagsPlugin.php
@@ -41,7 +41,7 @@ class TagsPlugin extends \Sabre\DAV\ServerPlugin {
 	public const NS_OWNCLOUD = 'http://owncloud.org/ns';
 	public const TAGS_PROPERTYNAME = '{http://owncloud.org/ns}tags';
 	public const FAVORITE_PROPERTYNAME = '{http://owncloud.org/ns}favorite';
-	public const TAG_FAVORITE = '_$!<Favorite>!$_';
+	public const TAG_FAVORITE = ITags::TAG_FAVORITE;
 
 	/**
 	 * Reference to main server object
diff --git a/apps/files/lib/Service/TagService.php b/apps/files/lib/Service/TagService.php
index 9e5661eef6fcc..975d594003eb1 100644
--- a/apps/files/lib/Service/TagService.php
+++ b/apps/files/lib/Service/TagService.php
@@ -54,6 +54,9 @@ public function updateFileTags($path, $tags) {
 			throw new \RuntimeException('No homeFolder set');
 		}
 
+		// Only handle the favorite tag
+		$tags = array_filter($tags, static fn (string $tag): bool => $tag === ITags::TAG_FAVORITE);
+
 		$fileId = $this->homeFolder->get($path)->getId();
 
 		$currentTags = $this->tagger->getTagsForObjects([$fileId]);
diff --git a/apps/files/tests/Service/TagServiceTest.php b/apps/files/tests/Service/TagServiceTest.php
index b914489053fbc..97e78d2b746c8 100644
--- a/apps/files/tests/Service/TagServiceTest.php
+++ b/apps/files/tests/Service/TagServiceTest.php
@@ -82,8 +82,7 @@ protected function tearDown(): void {
 	}
 
 	public function testUpdateFileTags(): void {
-		$tag1 = 'tag1';
-		$tag2 = 'tag2';
+		$tag1 = ITags::TAG_FAVORITE;
 
 		$subdir = $this->root->newFolder('subdir');
 		$testFile = $subdir->newFile('test.txt');
@@ -92,26 +91,17 @@ public function testUpdateFileTags(): void {
 		$fileId = $testFile->getId();
 
 		// set tags
-		$this->tagService->updateFileTags('subdir/test.txt', [$tag1, $tag2]);
+		$this->tagService->updateFileTags('subdir/test.txt', [$tag1]);
 
 		// Sync to reload tags
-		$this->tagger->addMultiple([], sync:true);
+		$this->tagger->addMultiple([], sync: true);
 		$this->assertEquals([$fileId], $this->tagger->getIdsForTag($tag1));
-		$this->assertEquals([$fileId], $this->tagger->getIdsForTag($tag2));
-
-		// remove tag
-		$this->tagService->updateFileTags('subdir/test.txt', [$tag2]);
-		// Sync to reload tags
-		$this->tagger->addMultiple([], sync:true);
-		$this->assertEquals([], $this->tagger->getIdsForTag($tag1));
-		$this->assertEquals([$fileId], $this->tagger->getIdsForTag($tag2));
 
 		// clear tags
 		$this->tagService->updateFileTags('subdir/test.txt', []);
 		// Sync to reload tags
-		$this->tagger->addMultiple([], sync:true);
+		$this->tagger->addMultiple([], sync: true);
 		$this->assertEquals([], $this->tagger->getIdsForTag($tag1));
-		$this->assertEquals([], $this->tagger->getIdsForTag($tag2));
 
 		// non-existing file
 		$caught = false;
diff --git a/lib/private/Tags.php b/lib/private/Tags.php
index ec06259db70ce..b11ac49ce0428 100644
--- a/lib/private/Tags.php
+++ b/lib/private/Tags.php
@@ -194,17 +194,12 @@ public function getTagsForObjects(array $objIds) {
 	 */
 	#[\Override]
 	public function getIdsForTag($tag) {
-		$tagId = false;
-		if (is_numeric($tag)) {
-			$tagId = $tag;
-		} elseif (is_string($tag)) {
-			$tag = trim($tag);
-			if ($tag === '') {
-				$this->logger->debug(__METHOD__ . ' Cannot use empty tag names', ['app' => 'core']);
-				return false;
-			}
-			$tagId = $this->getTagId($tag);
+		$tag = trim((string)$tag);
+		if ($tag === '') {
+			$this->logger->debug(__METHOD__ . ' Cannot use empty tag names', ['app' => 'core']);
+			return false;
 		}
+		$tagId = $this->getTagIdByIdOrName($tag);
 
 		if ($tagId === false) {
 			$l10n = Util::getL10N('core');
@@ -504,18 +499,15 @@ public function removeFromFavorites($objid) {
 	 */
 	#[\Override]
 	public function tagAs($objid, $tag, ?string $path = null) {
-		if (is_string($tag) && !is_numeric($tag)) {
-			$tag = trim($tag);
-			if ($tag === '') {
-				$this->logger->debug(__METHOD__ . ', Cannot add an empty tag');
-				return false;
-			}
-			if (!$this->hasTag($tag)) {
-				$this->add($tag);
-			}
+		$tag = trim((string)$tag);
+		if ($tag === '') {
+			$this->logger->debug(__METHOD__ . ', Cannot add an empty tag');
+			return false;
+		}
+		$tagId = $this->getTagIdByIdOrName($tag);
+		if ($tagId === false) {
+			$this->add($tag);
 			$tagId = $this->getTagId($tag);
-		} else {
-			$tagId = $tag;
 		}
 		$qb = $this->db->getQueryBuilder();
 		$qb->insert(self::RELATION_TABLE)
@@ -553,16 +545,12 @@ public function tagAs($objid, $tag, ?string $path = null) {
 	 */
 	#[\Override]
 	public function unTag($objid, $tag, ?string $path = null) {
-		if (is_string($tag) && !is_numeric($tag)) {
-			$tag = trim($tag);
-			if ($tag === '') {
-				$this->logger->debug(__METHOD__ . ', Tag name is empty');
-				return false;
-			}
-			$tagId = $this->getTagId($tag);
-		} else {
-			$tagId = $tag;
+		$tag = trim((string)$tag);
+		if ($tag === '') {
+			$this->logger->debug(__METHOD__ . ', Tag name is empty');
+			return false;
 		}
+		$tagId = $this->getTagIdByIdOrName($tag);
 
 		try {
 			$qb = $this->db->getQueryBuilder();
@@ -671,6 +659,24 @@ private function getTagId($name) {
 		return false;
 	}
 
+	/**
+	 * Get a tag's ID from either its ID or its name.
+	 *
+	 * A numeric value is only accepted as ID if it is the ID of one of the loaded tags.
+	 *
+	 * @param string $tag The tag ID or name to look for.
+	 * @return string|bool The tag's id or false if no matching tag is found.
+	 */
+	private function getTagIdByIdOrName(string $tag) {
+		if (is_numeric($tag)) {
+			$key = $this->getTagById($tag);
+			if ($key !== false) {
+				return $this->tags[$key]->id ?? false;
+			}
+		}
+		return $this->getTagId($tag);
+	}
+
 	/**
 	 * Get a tag by its name.
 	 *
diff --git a/tests/lib/TagsTest.php b/tests/lib/TagsTest.php
index e2ef9eb25c024..2a69e8d87566a 100644
--- a/tests/lib/TagsTest.php
+++ b/tests/lib/TagsTest.php
@@ -306,6 +306,38 @@ public function testUnTag(): void {
 		$this->assertEquals(0, count($tagger->getIdsForTag('Family')));
 	}
 
+	public function testTagById(): void {
+		$tagger = $this->tagMgr->load($this->objectType);
+		$tagId = $tagger->add('Family');
+
+		$this->assertTrue($tagger->tagAs(1, (string)$tagId));
+		$this->assertEquals([1], $tagger->getIdsForTag('Family'));
+		$this->assertEquals([1], $tagger->getIdsForTag($tagId));
+		$this->assertTrue($tagger->unTag(1, (string)$tagId));
+		$this->assertEquals([], $tagger->getIdsForTag('Family'));
+		$this->assertEquals(1, count($tagger->getTags()));
+	}
+
+	public function testTagByNumericValue(): void {
+		$otherTagger = $this->tagMgr->load($this->objectType, [], false, self::getUniqueID('user_'));
+		$otherTagId = $otherTagger->add('Family');
+		$this->assertTrue($otherTagger->tagAs(1, 'Family'));
+
+		$tagger = $this->tagMgr->load($this->objectType);
+
+		// Treated as the name of an own tag
+		$this->assertTrue($tagger->tagAs(2, (string)$otherTagId));
+		$this->assertTrue($tagger->hasTag((string)$otherTagId));
+		$this->assertEquals([2], $tagger->getIdsForTag((string)$otherTagId));
+		$this->assertEquals([1], $otherTagger->getIdsForTag('Family'));
+
+		$tagger->unTag(1, (string)$otherTagId);
+		$this->assertEquals([1], $otherTagger->getIdsForTag('Family'));
+
+		$tagger->unTag(2, (string)$otherTagId);
+		$this->assertEquals([], $tagger->getIdsForTag((string)$otherTagId));
+	}
+
 	public function testFavorite(): void {
 		$tagger = $this->tagMgr->load($this->objectType);
 		$this->assertTrue($tagger->addToFavorites(1));