Unbound failing after ~30 minutes on 23.7.2

[bbin]

I'm running 23.7.2 on a brand new Protectli VP4670.  After a clean reboot, things seem to be running fine for roughly 30 minutes, after which unbound seems to be unable to resolve anything.  When I take a look at the logs, I see entries similiar to this:

2023-08-23T22:14:59-05:00   Error   unbound   [72972:2] error: SERVFAIL <connectivitycheck.gstatic.com. AAAA IN>: all the configured stub or forward servers failed, at zone . no server to query nameserver addresses not usable have no nameserver names

I was using DOT with cloudflare, but have also just switched to regular DNS resolution using system resolvers and get the same result.  After rebooting, unbound seems to be able to resolve again.

Has anyone else run into this?  franco or others with the project - any ideas?