You mention 'iMac', there is lmited driver support direct from AMD.
There was/is a 3rd party site with somewhat modified drivers which may be better to look for?
Don't recall offhand what it was named/renamed.
My PC- Ryzen 5 5600x, B550 aorus pro ac, Hyper 212 black, 2 x 16gb F4-3600c16dgtzn kit, NM790 2TB, Nitro+RX6900XT, RM850, Win.10 Pro., LC27G55T.