Long-running browser times everything out

TBB 12.0.1 (not observed earlier) on Win10, after running non-stop for some (3-5) days begins showing "Connection timed out" for everything. Tor logs are cut at some point earlier that day (probably the same moment timeouts began, but I'm always AFK). Killing Tor and letting browser restart it changes error to "Proxy server refusing connections" - maybe a separate bug?