Big Sur on M1 (and possibly on Intel) maintains a persistent, hardware-serial-number linked TLS connection to Apple (for APNS, just like on iOS) at all times when you are logged in, even if you don't use iCloud, App Store, iMessage, or FaceTime, and have all analytics turned off.
There's no UI to disable this.
This means that Apple has the coarse location track log (due to GeoIP of the client IP) for every M1 serial number. When you open the App Store app, that serial number is also sent, and associated with your Apple ID (email/phone) if you log in.
Apple knows when you leave home, or arrive at the office, or travel to a different city, all with no Apple ID, no iCloud, and no location services.
This has always been the case on all devices using iOS, too.
This change is essential for blocking such traffic, and I'm glad for it, but there is a long way to go when it comes to pressuring the pro-privacy forces inside of Apple to do more.