I get this error with increasing frequency:

I'm not doing the abortion, Confluence does. None of my other web applications has a connectivity issue. It has happened on different pages. I would not call these pages huge. They would probably fit on 3-4 sheets of A4 or similar.
I have Grammarly connected, but don't think that would be related.
Steps to reproduce:
- Open a page for editing
- Editing usually works of for a while
- (Often the cursor goes invisible)
- Sporadically I get the 'We lost connection with you, hold on"
- After a while, the error message above occurs.