Not exactly a fix: but after setting everything to low, no DLRR, No cross platform or trade, no RT and trying the manual VRAM at 24GB I was still crashing within ~30 mins.
Today, turned VRAM to 100 GB (98304MB was the specific value i used, i just 4x the VRAM suggestion in one of the other threads). I was able to play avoiding crashes. I restarted after 2 potions (so at least an hour, but didnt stress test for further). No crashes when I did this, so enough to not lose an entire potion by clicking one then going to the blacksmith. This is a workaround, not a fix
Clearly a bug, should never need to dedicate that much VRAM. Not sure if it mattered, but for sake of it, I had another ~150GB free on my SSD after the VRAM claim. All a single SSD.
Original VRAM recco thread w/ instructions that i changed from ~24GB to ~100GB starts here: Diablo IV has run out of memory - #103 by DTMAce-1687
Only difference i did is 4x the allocation and clear out a ton of space (had at least a 2x buffer beyond what i set, on the HD I set it on).
Hope that helps sometime until we get a true fix. i9 / 4080