It still makes me jittery how much stuff they've packed into the client. The RCE vulnerability in their windows client is pretty strong indicator that things are moving a bit too fast for comfort.
wireguard is a linux-first solution and all of the windows stuff for it is subgrade, and probably will continue to be for awhile. Still selling plenty of anyconnect/globalprotect have a stranglehold on windowsland and probably will for a long time.
There were a few things going on with that issue you mentioned; one of them is the way the wrapper library was written, the other was with some stuff in the GUI client that was happening on a background goroutine but shouldn't have been. That should be fixed in the current stable release.
As for the Windows client in general, it is going to be receiving a lot of love over the next few months!
I'll have to check out the bug sometime, but it sounds like it's just bad luck with goroutine scheduling and the order things execute in, in a goroutine that isn't locked to a thread. I can see it going unnoticed on older versions of Go (especially prior to weirder things like usermode preemption.)
https://github.com/tailscale/tailscale/issues/4133
That said, I'm not near the computer where I have it occur right now to check.