TikTok has recently been testing new features related to AI and also Memes. This feature appears to only be available if the user uploads a photo. Before sharing there are editing tools such as text, stickers, Effects, filters and AI Meme.
The Meme AI is seen to scan a user uploaded picture, then a new caption will be generated that matches the picture. After a caption is generated the user also has the option to rearrange. TikTok also warns that generated captions may not be polite or appropriate for users.
This AI Meme feature is not new because previously users could use Effects created by other users for more or less the same feature. It's just that the version I'm showing is official by TikTok itself which is available on both iOS and Android versions.