Your certificate is invalid.
Aug 28, 2023 08:18:35.951 [26316] DEBUG - BPQ: [Idle] -> [Starting]
Aug 28, 2023 08:18:35.956 [26316] DEBUG - FeatureManager: Using cached data for features list
Aug 28, 2023 08:18:36.606 [26316] ERROR - [CERT] PKCS12_parse failed: error:0308010C:digital envelope routines::unsupported
Aug 28, 2023 08:18:36.607 [26316] ERROR - [CERT] Found a certificate, but couldn't install it.
Aug 28, 2023 08:18:36.607 [26316] DEBUG - MyPlex: mapping state set to 'Unknown'.
Aug 28, 2023 08:18:36.607 [26316] DEBUG - Relay: read 12 cached entries from hosts file
Is this your certificate or the Plex one?
If your own certificate, there have been some changes for certificates because SSL v1.1.1 was expiring (30-Sept-2023)
Info -
Your Plex certificate looked ok but I reset it anyway.
Please address the personal certificate if appropriate
then restart PMS
