Images only showing in thumbnail size

I have a page that shows all the participant information including the images they have uploaded. When that page is accessed the images used to be displayed full size. Now just a thumbnail is displayed. I have updated WordPress and this plugin and I have no idea what has changed. Can anyone point me in the right direction? The site is https://www.hellsoldfarts.com. Thanks

https://www.ads-software.com/extend/plugins/participants-database/