Thumbnail preview in grid wiget

Hi friends!

Help please with fixing the problem. The preview thumbnails in grid wiget in magazine front page started to show as a rectangle instead of small square sience I started to just cut preview pictures in photoshop instead of resizing as I did before but maybe it is not the reason because the same size and px in both ways changes. They must be shown as the settings let them I guess no matter what size they have. Any help appreciate. Thank you.

Screenshot example: https://s003.radikal.ru/i202/1509/76/568b5d10e5af.png

The website: https://www.valkarbudo.ru/