SON OF A !!!!! YEARS LATER, I figured it out. It's fixed. NO MORE CRASHING.
So, I've mentioned in this thread and others that I had none of these issues until I replaced my older (RX580?) card with a RX Vega 56. I'm not sure of the timing exactly but somewhere around that time (or maybe exactly the same time) I also replaced my monitor with a VIOTEK GN32Q monitor because it supported Freesync. It turns out that it's somehow related to the lack of a monitor driver (with a proper list of supported resolutions and refresh rates, and possibly FreeSync range) for this generic monitor. Bear with me as I'm not at home on my gaming system to have to guess at the names of some of the thing below.
I stumbled onto this thread here. Like, him, the AMD driver showed my monitor's supported Freesync range at 90 to 144 Hz. FWIW, the game I really struggled with the crashing in is F1 2020 (Codemasters) and I was running Anti-lag, Enhanced Sync and FreeSync. My in car driving frame rates are, IIRC, in the 80's. I think the crashing was caused when the game would cross the 90 FPS range and then maybe the driver would try to switch to FreeSync.
I used the CRU utility to change the FreeSync range from "90 to 146Hz" to "40 to 146Hz". I also edited the monitor's Detailed resolutions to have only two settings supported, the 2k res at 60Hz and at 144Hz. This took a LOT of experimenting and reboots but in the end it's FIXED for me. I've even turned back on the TDR setting with no ill effects.
Changing this stuff isn't perfect. When sitting at the desktop (windows 10) I sometimes have to use the display settings to switch back and forth between the refresh rate, between 60 and 144 Hz. For the most part, once I'm done gaming I change it back to 60Hz.
I'm not sure how useful it would be for me to walk anyone through every step since you may not have the same monitors. This is a lesson for me to never buy a generic monitor again. This monitor, I love everything about it and it cost me only $450 while supporting FreeSync and the other certified FreeSync monitors at the time were starting at $900, IIRC. I am referring to monitors with a minimum size of 32" BTW.
I hope this helps get some of you on the right track. I can tell you that many nights, for the first 30 minutes my F1 game would hard lock (I had TDR turned off) sometimes 5 or more times then for whatever reason would usually settle in for the next few hours. Now, I've had at least 5 gaming sessions with not one crash of any kind.
Poor AMD, this was never even their fault and I can now see why while this problem wasn't that rare, there were many people having no issues like this. I'll criticize AMD in one way, they should have a good bug reporting tool that could have tracked that many of us have generic, uncertified (in terms of FreeSync) monitors.
Lastly, I'll help when I can but I'm super busy and it may be days until I can respond here. Suffice it to say, you need to understand how to use CRU, you need to know your monitor's supported refresh rates, and you need to have big cajones because you may end up having display issues if you mess up the CRU settings.
Oh, one more huge frustration I had with F1 2020. Until I figured out the problem, the game would sometimes be blurry and not smooth at all. I'd look in the games video settings and saw F1 had switched to a customer resolution that was just below the native 2k resolution (3840 x 2160 or something?). I couldn't fix this no matter what. It turns out that the per game AMD driver settings must not be on anything but Full Panel. Maintain aspect ratio was the setting that was causing this. It seemed like the right setting but in hindsight was not.