Originally published at: watchOS 7.6.1 Fixes Severe Security Vulnerability - TidBITS
Apple has rolled out the watchOS 7.6.1 to fix a severe security exploit that was patched in iOS 14.7.1, iPadOS 14.7.1, and macOS 11.5.1.
What do you do if your 4. generation watch does not say that an update is available? Mine says it has version 7.6 (18U63) and no update available.
Did you update your iPhone first?
My iPhone’s version is 15.0. Could that be the culprit? Being in beta-state?
Ah, that’s it alright. Watch updates roll straight after you update your iPhone.
Except when it doesn‘t 
It seems entirely likely that running the iOS 15 beta would prevent non-beta versions of watchOS from being available.