naeaje To be precise, There isnt any issue with template due to which @saguaros and I had suggested to switch over to default joomla template and then assign the banner to specific position and probably, you will notice similar issue with socialads banner in default template, too as there isnt media-query css being added for specific banner
Banners from banner component are appearing fine due to somewhat css rule-set as suggested below are already added in external css file
Usually, External css file reference are used for declaring the styles of certain elements of component which come compiled with the zip file of extension package
For instance, You can try add this to custom.css file and will see the social-ad appearing fine in responsive mode. Ref: screenshot
@media screen and (min-device-width: 320px) {.adtype img{width:100% !important;}}
Kindly ensure to clear your browser cache if changes dont reflect