And plenty of plugins which do clean up after themselves.
The warning is there and can not be turned off, it’s a WordPress thing.
Anyway, partial restoring from backups is not something I can help you with. But usually you need to restore the whole backup to then get a part of it because of how it’s packaged/zipped/compressed or whatever.
You can make a ‘test’ or temporary site for that on a subdomain or some kind of localhost setup if you want. No need to disrupt the live site for that 😉