Hey, I have the same issue with my enoceanpi addon in my RaspberryPi 4, I needed to find out after openhabian provided openhab 4 as release packages … on my system.
Bridge is properly initialized by OS, serial settings for RPi remained the same:
[ 1.570848] fe201000.serial: ttyAMA0 at MMIO 0xfe201000 (irq = 35, base_baud = 0) is a PL011 rev2
With openhab 4 packages I get same messages, looping:
==> /var/log/openhab/openhab.log <==
2023-07-24 23:11:52.894 [INFO ] [ernal.transceiver.EnOceanTransceiver] - Transceiver shutdown
2023-07-24 23:11:52.904 [INFO ] [ernal.transceiver.EnOceanTransceiver] - EnOceanSerialTransceiver initialized
2023-07-24 23:11:52.908 [INFO ] [ernal.transceiver.EnOceanTransceiver] - EnOceanSerialTransceiver RX thread started
2023-07-24 23:11:52.909 [INFO ] [nternal.handler.EnOceanBridgeHandler] - EnOceanSerialTransceiver RX thread up and running
==> /var/log/openhab/events.log <==
2023-07-24 23:11:52.896 [INFO ] [ab.event.ThingStatusInfoChangedEvent] - Thing 'enocean:bridge:enoceanpi' changed from OFFLINE (CONFIGURATION_PENDING): trying to get bridge base id... to OFFLINE (CONFIGURATION_PENDING): opening serial port...
2023-07-24 23:11:52.908 [INFO ] [ab.event.ThingStatusInfoChangedEvent] - Thing 'enocean:bridge:enoceanpi' changed from OFFLINE (CONFIGURATION_PENDING): opening serial port... to OFFLINE (CONFIGURATION_PENDING): starting rx thread...
2023-07-24 23:11:52.911 [INFO ] [ab.event.ThingStatusInfoChangedEvent] - Thing 'enocean:bridge:enoceanpi' changed from OFFLINE (CONFIGURATION_PENDING): starting rx thread... to OFFLINE (CONFIGURATION_PENDING): trying to get bridge base id...
Thanks for killing my relatively stable setup on Monday evening with that package move, I wanted to decide myself when to update to OH4 … 
Don’t know if I can easily switch back to OH3 packages, as I needed to modify runtime.cfg comprehensive for OH4 …