LND self-shutting down after missed responses from "chain backend"

Hey Community, wondering if anyone is experiencing the same: my Umbrel 5.1.0 on Raspi4 has frequent (every 4-12 hrs) “crashes” of LND.
Going into the log, i discovered these aren’t really crashes, but rather ordinated self-shutdowns of LND, because the “backend” suddenly stops responding to LND (not sure if “backend” means BTC Core here):

2022-08-31 11:50:07.817 [INF] HLCK: Health check: chain backend, call: 2 failed with: health check: chain backend timed out after: 30s, backing off for: 2m0s

and after another 2’ 30" and a 3rd missed response from the “chain backend” , LND decides to go for a controlled shutdown:

2022-08-31 11:52:37.818 [CRT] SRVR: Health check: chain backend failed after 3 calls
2022-08-31 11:52:37.819 [INF] SRVR: Sending request for shutdown
2022-08-31 11:52:37.907 [INF] LTND: Received shutdown request.
2022-08-31 11:52:37.907 [INF] LTND: Shutting down…
2022-08-31 11:52:37.991 [INF] LTND: Gracefully shutting down.
2022-08-31 11:52:38.012 [INF] NANN: Channel Status Manager shutting down
2022-08-31 11:52:38.013 [INF] HSWC: HTLC Switch shutting down

My node only has 7 channels, and negligible activity.

How to troubleshoot this further ?

I can manually restart LND and it comes up in a few mins.
ThunderHub, RTL and other apps resume normally after LND is up again.
Only Lightnening Terminal is never able to connect to LND anymore…
Some parts of it probably remain “stuck”…and i need to reboot the whole Umbrel so that LN Terminal starts to function again.