Distorted Thumbnails in Gallery Images

I have recently switched to using square photos for my website and have run into a problem with distorted thumbnails.
The following is a link showing a page with the distortion, as well as the main image being cut off at the bottom: https://leedowdyantiques.com/?listing=a-kling-solid-maple-desk-vintage-1960s-pedestal-style-estate

I have been unable to fix this when editing thumbnail options in Settings > Media. Any help with this issue would be greatly appreciated.

Lee Dowdy Antiques
https://leedowdyantiques.com