I created a test environment and there the problem is not present. I found then, that one image was not loaded on the live site. In the image name was the character “ü”. I changed it to “ue” and now the image loads also on the live site and the problem disappeared.
I’m wondering if there is a problem with the character set or if I simply shall avoid these characters in the file name? The site is on Cloudflare.
This thing starts to be a major problem for me. When I update posts where the image file name has special characters like ä ü ö , the page starts to flicker. Today I had 3 images with special characters on one page and I had to exchange the file names + all translations.
I’m wondering why the filenames with special characters worked before and now I have these problems.