(Superuser.com does not allow the word "Problem" in titles, hence asterisk)
After turning on my PC I noticed the Windows desktop notification area showed there were two notifications pending, opening that produced this message
Microsoft Account Problem
Select here to sign in to your Microsoft account to continue using apps between this device and your other devices.
I try to minimise the extent to which I grant large multinational corporations the right to sell my data or monitor my prediliction for trip-hop, so I regard this sort of vague yet ominous message with suspicion.
Additional info requested by comments:
Settings > Accounts > Sign-in options
When I turn on my PC, I log in with a local account. This is Windows 10 Home, no AD etc.
I don't use Microsoft services to any great extent. I use Windows 10 and let it apply security updates etc. I don't use Microsoft Office, Outlook, IE or Edge. I don't use MS cloud services or use their services to backup data, nor to synchronise data across devices.
Some years ago I set up an MS account since a business contact needed me to participate in a Teams meeting and also to receive a few encrypted emails over a period of a month or so (I recall as a guest via a web-browser rather than using an app?)
Does anyone know exactly what the notification means? What "apps"? What "devices"? What is meant by "between" in this context? For whom is this a "problem"? What have I been doing that I may not now "continue"? If I do not comply, what are the consequences for my use of Windows 10?