The behaviour can be seen in this test gallery: http://zs8skbavix.preview.infomaniak.website/reisen/berlin/
I'm having a hard time debugging this problem at the moment, because when I click on one of the images, it loads just fine. Interestingly, it will affect different images every time I load the page. I think it's related to the resizing of the image, as the web server's error log shows some PHP deprecation errors, such as "PHP Deprecated: Creation of dynamic property resizer::$render is deprecated" However, I've tried with PHP 7.4 to 8.2 - so if this is the right track, either something is wrong with my hosting or it's a rare bug. I'm also wondering if the images should not be cached and already present in the right sizes on subsequent pages visists.
Code
[Fri Jun 16 10:19:37.451120 2023] [fastcgi:error] [pid 88260:tid 140653191194368] [client 2a02:8071:8285:af20:4c09:5be6:cea0:33e5:0] FastCGI: server "/home/clients/d065a58118c82f0ed939361328465240/.config/apache/foto.dwaldmann.de/.fpm/php5.external" stderr: line 145; PHP message: PHP Deprecated: Creation of dynamic property resizer::$iptc is deprecated in /home/clients/d065a58118c82f0ed939361328465240/sites/customer/app/parsers/slir/index.php on line 146; PHP message: PHP Deprecated: Creation of dynamic property resizer::$source is deprecated in /home/clients/d065a58118c82f0ed939361328465240/sites/customer/app/parsers/slir/index.php on line 147; PHP message: PHP Deprecated: Creation of dynamic property resizer::$render is deprecated in /home/clients/d065a58118c82f0ed939361328465240/sites/customer/app/parsers/slir/index.php on line 201; PHP message: PHP Deprecated: Creation of dynamic property resizer::$cache_dir is deprecated in /home/clients/d065a58118c82f0ed939361328465240/sites/customer/app/parsers/slir/index.php on line 221, referer http://zs8skbavix.preview.infomaniak.website/reisen/berlin/