Two personal microsoft email addresses with identical config, but one contantly needs reauthentication

[waterwheels]

Hello, I'm hoping somone might have some pointers as to where I should look to troubleshoot this issue. I have one recent @outlook.com email address, and one extremly old @hotmail.co.uk email address, and the old one continually needs reathuentication. I have the same config for each:

[[email protected]]
permission_url = https://login.microsoftonline.com/common/oauth2/v2.0/authorize
token_url = https://login.microsoftonline.com/common/oauth2/v2.0/token
oauth2_scope = https://outlook.office.com/IMAP.AccessAsUser.All https://outlook.office.com/POP.AccessAsUser.All https://outlook.office.com/SMTP.Send offline_access
redirect_uri = https://localhost:7598
client_id = <the thunderbird client id>

They had been working fine for a long time, but again recently the ancient @hotmail.co.uk address has started needing reauthentication often. I'm using apple mail on a mac running macOS 11, and I have compared the configuration on the app end and as near as I can tell it's the same as well.
I can't for the life of me work out what's different between the two accounts, although I think I recall reading that really old MS email accounts can behave weirdly? I have tried using an alias for the old account that's @outlook.com, but I can't seem to get the initial setup to go through. today when I tried, the newly added account seemed to dissapear when I finished setting it up in Mail.

The error I'm getting when the @hotmail.co.uk account fails is this one:

Caught exception while requesting OAuth 2.0 credentials for account [email protected]: {'error': 'invalid_grant', 'error_description': "AADSTS70000: The provided value for the 'code' parameter is not valid. The code has expired. Timestamp: 2025-10-09 02:10:56Z", 'error_codes': [70000], 'timestamp': '2025-10-09 02:10:56Z', 'error_uri': 'https://login.microsoftonline.com/error?code=70000'}

(I've removed the Trace ID and correlation ID entries since I don't know if that's public or private info)
It seems like the old account isn't renewing its token properly, but I have no idea why or what to check to puzzle it out!

[simonrob]

I also have an ancient Hotmail account, but haven't run into this myself. The error message suggests that perhaps the expiration time provided when retrieving the code is not correct, or the proxy isn't handling this properly. Either way, this is something I'd need to see for myself to determine whether there's any way to resolve it. Unless you're comfortable sharing access to the account, there's not much I can do to debug I'm afraid.