Just picked up a '21 and one front screw was already rusted when I picked it up.
They told me they would get me some, but Toyota dealers are useless.
(First time I am ever using a front plate in a front plate state as they already installed the mount)
Anywho, I picked up some 316 black oxide coated stainless and titanium bolts for the plates and a few jars of Copaslip Molyslip for plate bolts and to go over some bolts on the underside as well.
An ounce of prevention...
'Just have a few days before I can plop the plates in.