In my personal experience with tiktok it will pigeonhole you rapidly. But overall the platform is heavy on silly and fun content (not sure if it intentionally maintained like that by the owners). So before you know it you are pigeonholed into extremely fun stuff (compared to tediously polarizing content on other big apps).

Now over time it might devolve into bad content if there is no higher level moderation to keep it on lighter side of things. I would personally be okay with not all platforms being totally democratic.