Reduced availability of HS v3 services compared with that of v2
I serve sshd behind HS v2 and v3 services and I have done for a long time. I've used both alpha, beta, and release builds of Tor 0.3.4 and 0.3.5 for this.
Per my experience, HS v2 services are almost always available for the client to connect to, but HS v3 services not so much. There are periods in which the client can't connect to v3 services (high CPU at client for a minute, then give up), while for the corresponding v2 service the connection is almost instant.
Of course I would prefer to use v3 services if I can, if I observe they have the same degree of availability, but while I can't, I keep defining them in pairs (v3 + v2), because I know the time will come for some unspecified reason I can't use them (for hours at a time), and I want to keep for myself a workable alternative.
If I'm the only one to notice this, perhaps it's because I like to exclude lots of countries in ExcludeNodes, both at server and client side, and perhaps this affects v3 services only, or not only but disproportionally (and perhaps no one uses like this so they don't know). But that's the focus on my other ticket, #27811 (moved), and I won't postulate that here again.
For the moment I've got no solution, other than in my experience HS v3 services are less available therefore less dependable than v2 services.