Have you inspected the browser developer console? Or can you enable detailed errors to get more verbose output in the developer console?

I have seen this only once, with one user in our Blazor Server application that is very large code base. I never successfully found the issue. The symptoms might be different than what you are seeing as well. Our one user that was having this was if they were on a different tab for about one minute then returned it would crash the circuit. The console would show an unknown error. It wasn't always 60 seconds either, like sometimes it would be fine. It didn't matter the page etc. Again, it was only one user.

The next day, when I went to put in more effort to troubleshoot it, the problem was gone and has never come back since.