Help with subscribe window picture

Hello! Many of you have helped me so much and I had one more thing I needed assistance on. When you press the “subscribe” button on my website, the profile picture at the top shown here is cropped for some reason, any know how regarding fixing this? I apologize if this is not the right section to post in but I would love the help. My website is if it helps to view it there instead of the picture I put below. Thanks!

This is Portal, which is a separate app that runs on top of Ghost. It’s not easily tweaked with code injection or theme edits. The best workaround would be to load a different icon, one with more whitespace, so that when Portal tries to crop it to square, you still like what you get.