Calender visual Bug?

Configuration
1

Hi,

I have a Problem with the Calender. In PC and mobile Devices are the same Problem.
I open home Assistant first time, all is fine. I swap between the sites, the Calender is broken.

Often logbooks are do similar (endless loading icon)

Home Assistant is installed over Docker Container with nginx proxy Manager reverse proxy.

Screenshot_20231030_105335_Home Assistant
Screenshot_20231030_105335_Home Assistant2000×1200 118 KB

Screenshot_20231030_104716_Home Assistant
Screenshot_20231030_104716_Home Assistant2000×1200 125 KB

Any ideas?

Thanks