Games won't work on 4k setup

Long tech problem coming… I did my best to be thorough but brief, but it's complicated.
I have a Vizio 65 inch p series, a Denon AVR-S540BT, and an Xbox Series X (and Xbox One X). My issue is that I get very weird errors when I try to get them to work together to play a game. The issue almost always starts after a game loads, never on boot
The errors change, but they include the screen temporarily or permanently flashing to "no signal", green screen, or weird hard to describe visual errors, most often game ruining, but sometimes, weirdly, not. The audio is usually affected as well, though sometimes, especially with the green screen, the audio seems to be working while the video is broken. The Xbox main page also typically works when I start the system up and I can go through the settings and calibrations, but when I got to a game is when the fun begins. The symptoms seem random. Turning everything off and on enough times sometimes fixes it, but only temporarily.
One weird symptom is that the "HDR10" flashes on my screen a lot, when changing between games, or even going to the menu in a game. If I run it through my receiver, various icons flash on and off when it is struggling, I believe they are for Dolby Vision, some game engine thing, and other special things that I admit I don't know.
Sometimes it seems that specific effects trip something and the screen blanks temporarily, but most often games are just unplayable. Also, while xbox menus work fine on start up, if I break it by trying to play a game, it is 50/50 whether I can get back to the menu without a restart.
TV, Xboxes, and receiver all seem to work fine with other stuff. The problems are more or less the same on both Xboxes. And both Xboxes work fine on the only other TV I have, which is not 4k.
Microsoft support insisted that this was an HDMI issue, I can say for sure that is not given the number of times that I have swapped out cables
Other fixes I've tried:
Turning off and on most features I can think of on all devices. So HDR, Dolby Vision, CEC, etc. I am not an expert at this stuff so I mostly just flip stuff on and off, I cannot vouch for all the various combinations I have tried. But if I am aware of the feature or could find it in a menu, I attempted to turn it off.
Getting the TV replaced (twice). Same problem on all three, but they were all the same model.
Running the Xbox directly to the TV. This sometimes works in the short term but problems come back. They tend to be slightly different. While running through the receiver ends in a lot of flashing and various problems, most likely when run directly I just get a green screen on games with audio in the background. Most recently when I tried this it worked, but my Xbox insisted that my TV was not 4k capable and would not let me turn the setting on.
I am considering trying to get a new receiver since it's the only thing I haven't replaced, but considering I have issues without it in the mix, I assume it can't be the whole problem.
Having got all my various devices different places I am having trouble finding anyone to help me, and Microsoft just tells me it's my HDMI. (Truly, I have tried dozens, including the ones that came with the Xboxes for both connections)
If anyone could help me, I would be eternally grateful. This is all new gear, best setup I've ever had, and it doesn't work.

:)