Why don't thumbnails sometimes load after installing SSL?

Question

Web development

Good evening, after installing an SSL certificate on the gallery site, sometimes thumbnails of pictures are not loaded. This happens only with the last twenty pictures out of a hundred on the page, in random order. For each specific page, it is treated by reloading, but this is not the case at all.

The bug is absolutely unstable, it can appear both on every page and every 5-7 pages. You can try to catch it yourself, you just need to go through the pages and look at the last 20 thumbnails https://dota.gallery/art?tags=12&sort=date_desc&li...

The screenshot shows that everything is in order with the code and the links are all fully working.

If there is no solution, then at least tell me in which direction to look for information, because at the moment I have no idea what this could be connected with.