It is too soon to tell yet, whether this makes a difference.  But I had observed that if I turned off the network and ran standalone I experienced no crashes.  So yesterday, doing my monthly thing, I got in long enough to sync bank accounts and nothing else then killed the network.  Later I went into settings and disabled this one.

My thinking is the less network interaction the better.  So far today I had it up for a few minutes.  As I've been typing I notice Quickbooks is no longer running although I didn't intend to close it.  (I didn't get a crash prompt, it's just no longer active).  It's possible I did something like click the x on the window while tabbing around to different windows on my laptop.  If it does or does not appear more stable then I'll report back in a few days. 

In the meantime, the answer I was given by support is that QB 2021 lists Windows 10 compatibility not Windows 11, so I should not expect it to work - I should either pay to upgrade again and to either online or 2022 version.  However, as a nonprofit getting it for a discounted rate via techsoup, the latest available version is 2021.  So I have to live with it or find an old laptop/desktop somewhere and load it up there.  For the moment I am working around the issues, but I would rather they support the product.