Category builtin

something strange happens, that I had never noticed before. if I go to this website the upper banner which is an image, it is not displayed to me. since this is a site of models to download, if I click on those in jpg I see a message blocked site, category builtin, while the pdf I can download them

The top image, named banner, is (also) blocked by adblockers.
The web content filter has the builtin category enabled and urls are matching (model)+.*.jpg expression:

# db contentfilter getprop default BlockBuiltinRules 

# grep model /var/squidGuard/blacklists/custom/builtin/expressions