Comment 8 for bug 1917705

This is an unfortunate consequence of a decision by Google to restrict access to the sync API to Chrome only (which explains why in comment #3 you're seeing that chrome 89 on linux works fine).

There's a lengthy discussion with details here: https://groups.google.com/a/chromium.org/g/chromium-packagers/c/SG6jnsP4pWM/m/Y73W4CecCQAJ.

I am quoting the part that's relevant for end users:

 « What does this mean for my users?

Users of products that are incorrectly using these APIs will notice that they won't be able to log into their Google Accounts in those products anymore.

For users who accessed Google features (like Chrome Sync) through a 3rd-party Chromium-based browser, their data will continue to be available in their Google Account, and data that they have stored locally will continue to be available locally.

As always, users can view and manage their data through Google Chrome, Chrome OS, and/or on the My Google Activity page, and they can also download their data from the Google Takeout page, and/or delete it from this page. »

I'm afraid (and sorry) there's nothing that can be done from a packaging perspective to mitigate this regression. Reverting the snap in the stable channel wouldn't help, because it's not a version problem. The official announcement states that starting March 15 attempts to log in will fail anyway.

I suppose that users that can't do without the profile sync feature will need to move on to using the official chrome package distributed by Google, instead of chromium (which is probably what Google wants, really).