Do these "missing favourites" happen to anyone else?

Kind of exposing my Tiktok favourites here lol, but I have to ask.

This has been happening to me for almost a year now, where I'll save certain videos on my phone to my favourites, but when I go to rewatch them they aren't there. The only way to see them again (without searching for the creator's account and manually finding each video) is to log onto the same account on my laptop!

No one else I've mentioned this to has experienced this. Is it just me? Does anyone know what's causing this?? Is there some weird mobile setting that would cause this? As you can see, the videos it happens to are completely random.