Well, that was fun, just noticed an "Unknown" network extension in MacOS settings and it turned out to be protonvpn which I'd uninstalled via cleanmymac.
Had to follow:
- https://developer.apple.com/documentation/systemextensions/installing-system-extensions-and-drivers#Examine-the-Installed-System-Extensions
- https://developer.apple.com/documentation/security/disabling-and-enabling-system-integrity-protection
To fix, with multiple reboots
