Quick update: Server is stable for like 20 hours now.
ViewStateSync now actually threw an exception like in the mentioned other thread above.
Nov 17, 2024 19:34:36.543 [215252090048] DEBUG - [ViewStateSync] Starting
Nov 17, 2024 19:34:36.543 [215252090048] DEBUG - [ViewStateSync] Fetching user tokens
Nov 17, 2024 19:34:36.631 [215252090048] DEBUG - [ViewStateSync/HCl#2c] HTTP requesting GET https://plex.tv/api/v2/server/users/services?auth_token=xxxxxxxxxxxxxxxxxxxx
Nov 17, 2024 19:34:36.972 [215211252928] DEBUG - [HttpClient/HCl#2c] HTTP/1.1 (0.3s) 200 response from GET https://plex.tv/api/v2/server/users/services?auth_token=xxxxxxxxxxxxxxxxxxxx
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync] Got token for user REDACTED (REDACTED)
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync] Got token for user REDACTED (REDACTED)
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync] Got token for user REDACTED (REDACTED)
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync] Got token for user REDACTED (REDACTED)
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync] Got token for user REDACTED (REDACTED)
Nov 17, 2024 19:34:37.282 [213415455936] DEBUG - [ViewStateSync/HCl#2d] HTTP requesting GET https://plex.tv/api/v2/server/users/REDACTED/view_state_sync
Nov 17, 2024 19:34:37.349 [215211252928] DEBUG - [HttpClient/HCl#2d] HTTP/1.1 (0.1s) 200 response from GET https://plex.tv/api/v2/server/users/REDACTED/view_state_sync (reused)
Nov 17, 2024 19:34:37.412 [213415455936] ERROR - Promise destroyed without handling exception: %s
That Exception was ~3min after last crash and ~1min after process start.
No new requests since then have been logged.