To get your bug fixed faster please try to answer the following questions:
Which browser, operating system and versions of those are you using?
Chrome Version 83.0.4103.116, macOS 10.15.5
iPhone, iOS 13.5.1
What are the steps you took that lead to the bug?
I’m just testing the app. So I restored my backed up pages, and that worked.
Then it looked like I had to re-pair my mobile device. When I did, the sync took a long time but eventually ended in failure. I tried twice, with the same error.