How to prevent images to get resized to a max of 572px in height?

When inserting on a page an image that is more than 572px in height, it get resized automatically to a max of 572px tall – and not always resizing the width accordingly.
I first thought it was a question of trying to use full width page. Nope, even on standard pages, images get resized if they are > 572px in height.
Can someone help me as to where in a child theme I should make the required modifications to allow for showing more than 572px, i.e. the full height of my pictures? Thanks!