Cannot access Zigbee2MQTT through Safari & domain but through local access or different browser

I am running an update to date install of HA and Z2M with several devices.

Since a few hours and after some config changes for some Zigbee devices (renaming, pairing) I cannot access the Z2M web interface anymore when I am logged into HA through my domain when using Safari, however I still can open the Z2M web interface when I log into HA through homeassistant.local, IOS, macOS app or when I use a different browser (e.g. Chrome) or a private session in Safari.

I cleared the cache, restarted HA, revoked all tokens - no change. Other adding are loading in Safari, e.g. File Editor.

Any advise?

I tested this with another Mac and the same user account, still the same behavior in Safari. When I open Z2M, the frame on the right stays empty.

With the same user in the IOS app Z2M opens and I can see all devices etc.

Anyone any idea?

I have a similar problem for the last two weeks. The Zigbee2MQTT page is very old fashioned formatted in HTTP web style. With Chrome, I can see the normal UI. Strange. Thie strange behaviour started with one of the last updates.
I assume a similar reason as your problem… .
Sorry, that I cannot help you directly.