Hi Flaviocopes, I just ran into exactly the same error trying to change my password in the admin profile with this non super user - they have access to admin, but not super, but they don’t seem to be able to change their own password…
Yes, currently this is a problem. Already tracked in https://github.com/getgrav/grav-plugin-admin/issues/713. Basically any user with admin.login should be able to edit his (and only his) profile. Make your +1 on that issue to raise it, I need to take a look at fixing this problem.
About that other issue, is that in a page? or in a Configuration panel? Which permissions does the user have?