hi @marketingsog ;
I tested the site with Autoptimize disabled (by adding ?ao_noptirocket=1 to the URL) in a small viewport and the images remain small for me:
The width of the image is set in a Divi stylesheet (wp-content/et-cache/1376270/et-core-unified-1376270.min.css), so best approach would be to add below CSS in Appearance -> Customize -> Extra CSS (you might have to add an !important flag after the unset, not sure about that one)
@media only screen and (max-width: 980px) {.et_pb_post a img {width: unset;max-width: 100%;}}
hope this helps,
frank
thanks it was a css width in extra code. I added !important and now it has the correct size