Outlook email repeatedly requires password on iPhone
I have my Outlook.com email address synced to the Apple Mail app on my iPhone. I haven't had any problems with this setup in years.
However a week or two ago I started getting prompts to re-enter my password. Once I re-entered my password, the email synced properly for a few hours... then the password prompt came up again.
This has continued every day since it started, and is starting to become infuriating.
In an attempt to resolve the issue, I have deleted the relevant email account from my Settings app, and reentered it again. I have also made sure my phone is up-to-date with iOS 14.2.
Strangely, this has also started happening to my wife (on her work and personal phones) and both my parents. Everyone is using both Outlook.com email addresses and Apple devices, so it's hard to know which end is causing the problem.
Any help would be gratefully appreciated - thanks in advance!
PS: I will not download the dedicated Microsoft Outlook iPhone app.
[Re-Titled by Moderator]
iPhone XS, iOS 14