Limit functionality to specific thumbnail size(s)

Square thumbnails are helpful for woocommerce shop:
https://michaelezra.com/product-category/unimpossible
Thumbnail size here is 300×300

But they become a problem for masonry image galleries:
https://michaelezra.com/portfolios/unimpossible
The gallery images here are larger, theme-generated medium resolution.
There has to be a way to bypass creating squares for these types of images, as it ruins visual presentation of galleries.

Please help! (urgently:))
Thanks!