Probably move on to YouTube Shorts or Instagram reels.
Likely YouTube. While neither are great, between Google and Meta, Google's got the better reputation. YouTube also has a larger audience, because it includes a ton of users who wouldn't fall under traditional social media usage. Reels might be used as a periphery platform to drive more people to their main channel on YouTube.
Any TikTok creator who moves to Instagram full-time is either shooting themselves in the foot, or got a good contract from Meta.
I do like the YouTube integration. A good chunk of them have a link to a main long form video which is nice when you don't want to watch a video in 50 parts. You can scroll and be like, that's a cool project let me watch the full 30 mins video.
Are YouTube shorts still 1 minute maximum? Until that changes, I don't think they'll be a viable replacement since content longer than a minute seems to be the sweet spot for a sizeable amount of Tiktok's user base. Especially when it comes to informative or political content.