Very Low Resolution Image Previews

I’m noticing that the image previews (thumbnails) that appear after upload are extremely low resolution. I don’t know if it’s because the plugin is squeezing a horizontal image into a square container and it’s affecting the image clarity, or if it’s a result of some kind of compression, but the result is a preview that’s overly blurry and very low quality. Is there any way to fix this?

https://www.ads-software.com/plugins/ultimate-member-gallery/