Hi at all,
a short update from my side. I guess i figured out what caused the problem. Obviously I was running into some trouble with java garbage collection. I use a Raspi 4 with 8 GB RAM and the java heap space was set to default by openhab. Since changing this setting to some more space (1GB) I could not longer monitor this behaviour. So all works great!
Some usefull links to this topic for me are shown below:
java - What are the -Xms and -Xmx parameters when starting JVM? - Stack Overflow
I hope this helps other guys in future.
Best regards!
Stefan