I think my HA is also affected by this. I haven’t done any firewall snooping and I’m not using pFsense, but I also have a timer based on Kodi’s ”turn_off” event, and the symptom of repeated ”turn_off” events match. The workaround from @ChopperRob above also seems to work.

(Probably unrelated, but I’ve also noticed that my ”turn display on when Kodi becomes idle” stops working when my LAN/WLAN gets very congested (such as when doing backups over the network). I’m using ”idle” because the log never shows a ”turn_on” event from Kodi; just ”idle”, ”playing” and the intermittently incessant ”turn_off” events.)