Comment # 12 on bug 110199 from jacobbrett+fd.o@jacobbrett.id.au

(In reply to Bennet from comment #11)
> Only kernel 4.19 works for me with 75hz , so probably seem to be a problem
> related to Free Sync.

I don't think it's Freesync-specific; I have Freesync turned off but suffer the
same issue at 75 Hz; working fine at 60 Hz, though (RX 580).