How can I correct cropped images on my collection page?

[Vince111]

Hi. Please help.

How can I fix, some of the photos looks like "cropped" on my collection page.

See the product named "zirkel" and "willow".

Also, it not only happens on main pages but also happens when you search it, it's always like that. 

Please help.

Website: maevincollection.com