I have seen this happen on Android when using the PWA with Firefox. If I open it, then switch to other apps, and then come back to it hours later, it immediately crashes. When I open it again, it will work fine, unless I switch away from it without closing it again for a few hours, where it will crash again.
Might be related to your issue, or it might be an issue with how Firefox does PWAs on mobile. I have seen a few other bugs with Firefox PWAs, so I assumed it was a Firefox problem.