I've just managed to stop crashes and strange behaviours, so I want to share what I did wich worked for me.
Steps to reproduce: Having a RX6xxx GPU in dual screen setup with at least one high refresh screen.
That gives you crashes, freezes, etc. and it's more noticeable on newer drivers.
Step 1: Disable browsers HW acceleration. This stoppped my computer from crashing when browsing.
Step 2: Limit refresh to 120hz (from 165). This reduced a lot other crashes, but not completely (75%?).
Step 3: Disable DPO in windows. This made the trick, over 1month now without a single crash in any circumstance.
Probably, at this point, I could enable HW for browsers again, but everything runs perfectly, so I don't want to take any chances.
I hope this could help someone.
Can't edit previous post.
There's a typo in step 3. I disabled MPO -> Multiplane Overlay.
I used a reg file provided by competitor GPU provider... seems that they have their own problems with it.