Maybe your users like to upload images in portrait mode. On small screens like on a Mobile this could result into unwanted style issues, as the image inside a location bubble need too much space.

To prevent this you could use the following CSS code to set a fixed image dimension (e.g. 4:3) and crop or scale the image inside:

@media (max-width: 768px) {
  .open-user-map .box-wrap .map-wrap .leaflet-map .leaflet-popup-content-wrapper .leaflet-popup-content .oum_location_image img {
    aspect-ratio: 4/3;
    object-fit: contain;
    object-position: top center;
    background-color: #eee;
  }
}

You could play around with the aspect-ratio or try object-fit: cover to crop the image.

With a future update we are planning to provide a new UX for the mobile view, so this may be just a temporary quick solution in the meantime.