For me, same behaviour with the snapshot build. I have openHAB 4.1.0 (build Build #3675).
The Shelly binding reports being 202310130405:
openhab> list -s |grep shelly
280 x Active x 80 x 4.1.0.202310130405 x org.openhab.binding.shelly
I’m seeing thread growth in bites of 8, and same symptom - associated with failed discovery and “WebSocket error” in the log at the time where the threads grow.
I think it makes sense to do some sort of WebSocket destroy as I noted in the above comment OH4 runs out of memory - #79 by PaulL1