If it’s just a matter of it not longer shrinking, it’s possible that something changed in the map’s custom sizing, either as a custom setting within the plugin or something created inline when you added the map element on the page.
It seems to stay at the same size, 584 x 300, on all views, overriding responsive scaling. Adding a max-width of 100% to the map element should fix it if that is the only issue. Does adding the below code to your advanced CSS resolve the issue for you?
div#custom-mapping-google-map-0 { max-width: 100% }