I recently tested a Radeon R5 240 (Oland) on Dragonfly 6.0 and noticed acceleration was disabled. It appears it was disabled with commit e8de9e9.
I rebuilt my kernel with acceleration re-enabled and it seems to be working fine. I'm using Xfce 4.16, Chrome 91 etc. Is it possible the underlying issue has been fixed incidentally? Is there anything specific I should test, or another GPU I could try that is known to exhibit issues? -Bill