No Cover Art in the Booklistings

Hello!

First of all, thank you for this wonderfull piece of software Kovid Goyal! It is very helpfull.

Since i updated to calibre version 7.0 i see no cover art in the book-listing-pages on the calibre server. The httpd-log shows that the files are requested and delivered. The covers are shown in the book-details-view. So they are available.
On the book-listing-pages instead of the covers the titles and authors are shown.


from the httpd-logs:
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3011/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3010/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3009/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3006/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3008/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3007/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3005/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3004/CB?sz=105x140 HTTP/1.1" 304 -
ip.red.act.ed - - [19/Nov/2023:17:20:02 +0100] "GET /calibre/get/thumb/3003/CB?sz=105x140 HTTP/1.1" 304 -

I have tried it with current versions of edge, firefox and chrome on win10 and fedora. I deactived the adblocker, tried to open the listings on localhost (as i have the calibre-server behind apache as proxy), but the cover art won't show up.

If i try the mobile-version under https://servername.tld/calibre/mobile the request is answered with a http 500 response:
ip.red.act.ed - - [19/Nov/2023:18:07:55 +0100] "GET /calibre/get/thumb/2989/CB HTTP/1.1" 500 -

What can i do to get the cover art shown again?
The calibre-server is running on fedora 36 (i know, i know, i should upgrade it, but there are unresolveable dependencies hindering me to do so.)

friendly regards
mattmaria