There are a few things that may contribute to this symptom.
One may be the Site could partially be to blame; if it uses an
"https" for some content, and less secure "http://" for others.
The browser may also have some factor in determining security.
Images & other items online need automatic verification to work.
Have to assume your Mac runs Safari ~ if system uses it as default.
You could try another modern browser, to see how that renders.
Depending on what else(?) may be happening in your Mac an idea
could be to get and run EtreCheck to see what shows; and post its
report into an ASC discussion is an option https://www.etrecheck.com/
Sometimes (rarely) when "blue?" happens in Firefox ESR in my Mac
I use Contextual Menu* to choose to 're-load image' to show item.
*mouse button (L or R) set to show Finder sub-menu.
An item I did find may offer clues..
• If Safari doesn't load a page or webpage items are missing - Apple Support
https://support.apple.com/en-us/HT204098
Not sure if this is why your Mac does not render some items or icons
correctly; so maybe browser or website have non-compliant settings.
Take care & good luck!🌞🎣