Microsoft Exchange emails not syncing with gmail app

I have a Moto g8 with Android 10. I use default gmail app to read my phone's gmail account as well as my two work emails (both MS Exchange/Outlook). I do not use the Outlook app for the latter. I have all accounts on manual sync, by choice: they sync **only** when I open the app and push emails (swipe down). This works fine with the gmail account. However, since some time ago (maybe 6 months or more), the two MS accounts do not sync. I need to go to Settings -> MS_account_name -> Incoming settings -> Next, and then I get the emails. This lasts for a few hours. Then I need to repeat. It seems like MS authentication for Gmail app is temporary. I have all phone apps updated. I've scrolled through lots of posts and webs but most advice is trivial (example ) and not relevant. Can't find a reply to this specific problem. Any ideas? Update: Has this anything to do with the removal of basic auth ? I tried deleting and reinstalling app, as suggested here , but no effect so far.