Server does not report an etag

I’m running Nextcloud 22.2.7 on a Hetzner VPM with current yunohost which means Debian 10.

Since I added an external storage, I have this Issue. The storage I removed, but the dialog is still there.
I haven’t noticed anything not working, though the desktop client shows a red x with the message “missing ETag”.

Here’s my log: {"reqId":"oPWZ0Z0oRGMmcAFuLFsD","level":2,"time":"2022-06-11T18:01:34+00:00","re -

Anyone an Idea what I could do?

Thanks for your hints.