We noticed that going from 1.28.0 to 1.30.0 and 1.30.1, Tailscale never appears as an updatable app. The only workaround I have found is to search for it in the App Store, open the app listing and then it is eligible for update.
I’ve experienced the same. I think there might be a bug related to updating running VPN apps. The Apple review process also adds an indeterminate amount of time. For this reason I switched to installing via the standalone binary at https://pkgs.tailscale.com/stable/#macos.
That’s not perfect either though. For some reason the standalone build is still at 1.30.0. And really you’re still manually checking for updates either way.