Required by role

Set required fields more precisely.

How to verify it it's in use on any fields (so you can remove it if desired)

I wanted to upgrade a site to D10 and there was a dependency from required_by_role on required_api, which was not yet D10 compatible. I wasn't sure if I was even using required_by_role on any fields - turns out I wasn't. There's no admin UI page overview which shows it's use, but you can just run a simple SQL query:

select * from config where data like "%required_by_role%";

(the config table is where all your field settings are stored).