Thumbnail Size Varies

As you can see here the size of two of my video thumbnails are differen tfrom the others https://howdoidate.com/videos/

I prefer the others which are 432x432px

The two that are different appear to be 432x360px.

I am at a loss to understand why since all the YouTube videos on this page were the same screen size i.e. 560×315.

Can you please enlighten me?

Thanks

Derek

https://www.ads-software.com/plugins/video-thumbnails/