Hey all - been racking my brain last few weeks with the same issue; macOS v12.1. Seems to apply to all drive types I have: thunderbolt-2 mechanical, usb-3 SSD and SD card. REALLY causing huge distractions for back-up etc.
Wondering if @Apple would like to chip in on this and give us a steer? I see similar questions outside the dev forum too. Would be great to have some formal acknowledgement and feedback to other potential actions.