Tor can be very unstable at times and there's nothing you can do about that.

I had heavy load since the blocks became busy few months ago. I had to shut down all other apps besides the core: bitcoin, lnd, electrs, thunderhub to get my load below 4.0.

Thunderhub will tell you who initiated the closure. It's under closed channels.

I'd recommend official umbrel telegram chat or their Forums to get detailed support!