https://bugzilla.kernel.org/show_bug.cgi?id=209457
--- Comment #12 from dark_sylinc@yahoo.com.ar --- Btw I reported that I was experiencing this too in my RX 560, however for me it went away with 5.8.15
I think my problem was unrelated to the one in this ticket, sorry.
Btw it may be worth writing down whether the GPU requires an extra PCIE power plug, as this may be relevant. My RX560 requires one (and is plugged).