Thunderbird has no connection to Windows (other than it will run on Windows, as well as Mac, Linux, etc.).
But Thunderbird has added the concept of a "Thunderbird cloud account" or something like that, and I think it will let you authenticate using credentials from other non-Thunderbird identities, such as Microsoft, maybe Facebook for all I know. The idea is apparently to allow a sort of "Single Sign-On" (SSO).
CAVEAT: I might have that wrong, I don't use any of that consumer-level SSO shite, I don't trust it. Sounds like a great way to have all your various service identities compromised at once.
My employer uses SSO but that's all high-security services and I don't have any choice about that.
Thank you for taking the time to reply and inform. When I first began using Thunderbird and Linux Mint, four to five years ago, the “Notes” folder was not present. After a year away from Linux Mint I returned to find this new development. I’ll stay with Mint but I’m looking for an Email service other than MS, possibly Mailfence. I’m leaving MS in the dust after forty-five years. Windows 10, Windows 11 as well as their software. Windows is spyware.