After days of searching this turned up and it’s from these forums from two years ago.
It turns out that since I use an MSI GPU somewhere Riva Tuner Statistics got installed.
After trying many different things this was the one that worked I simply shut it down.
Please let me know if this solves it for anyone else.
Not that it helps here but I’ve been using RTTS for years (over a decade, before UE4 was a thing) and never associated it with crashing. However, over the years there have been reports popping up, pointing at overlays and processes piggybacking Direct3D calls causing instability - not crashes per se but mostly interface issues.
These days it’s pretty much impossible (for me) to have the overlay up while in the UE5 specifically, though:
It cuts down editor fps by tenfold… All modes do. 
It’s fine logging stuff in the background.