Just as an update / FYI:

I'm still getting GPU timeouts on my AMD cards when mining on 2Miners.  The mining time is quite random and can be anywhere from 1-24 hours with 1 - 3 cards timing out at the same time in the mixed AMD/NVidia rig (4 AMD cards).  My AMD card running in windows will still crash occasionally, but it takes a while longer for it to happen (although the card quite often drops power to 15 watts in windows so there's a different pattern of disfunction which may hide the mining issue).

I waited on sending an update until I had updated the HiveOS kernel to the latest version, and it's still crashing.  Although, the new AMD drivers / Linux Kernel does seem to improve the performance on the AMD cards, or at least reduces the variability in performance, with the dips in hashrate being higher than before.

The new Linux kernel is letting the miner run CUDA 11.5 at a consistent 130+ MH/s, although with the temperatures climbing, I'm going to have to keep an eye on thermals vs. pure hash power; right now I can push the card to 134 - 137 MH/s average at the pool, but Memory Temps are creeping up into the 80's with ambient being 12-15 Celsius.