Prefixing table names with the app name is a simple way of letting multiple apps share the same database. Sharing the same database used to be really common, almost standard I’d say, when deploying on low-cost web hosts and also locally when working on multiple projects. I don’t let apps share databases anymore, but I still usually prefix table names anyway. Old habits die hard I guess, and for most ORMs it’s usually just a single config switch anyway.

Nothing strange about it. ORMs like Django name their tables <app name>_<model name> by default.

More plausible that there's WeChat_users and tiktok_users, as they don't just run 1 enterprise

Indeed it does. At a previous job we used to get rid of the convention. I've since thrown in the towel and said "meh"

more specifically for people who don't use it, the general naming is "module_modelname" (so for example "payments_paypaltransaction"). Django's term for what one might call a module is "app", which is also a bit of a loaded term, but the simple way of seeing it is that Django projects have many sub directories each managing a set of models (which map to DB tables, generally).

And douyin_users