Error while loading lovelace

Hello,
I have a problem with my Homeassistant. When I connect to my Homeassistant from outside I get the message „Error while loading lovelace“. I get it on my App, in my Browser, doesn’t matter which Device. It’s only the Dashboard, everything else, like settings works. When I connect local via IP address, everything works. Sometimes it also works with the Domain when I’m connected to the local WLAN.
This Problem is very random, because sometime
In my reverse proxy and Cloudflare setup I activated Websocket support.

I think this problem is since Core 2024.5.0, but I could also be random that this did happen at this time.

This setup worked for several weeks. I have no clue what the Problem could be now.

I‘m new here, please my patient. Tell me when I forgot some Infos. And sry for my bad english.

The browser logs: