Recover Files from Discontinued iOS App (Vee for Video)

For a period of time several years ago, I was using an app called Vee for Video (veeforvideo.com) to shoot video on my iPhone. The videos were accessible only through the app, but could be exported and saved to the native Photos app. I moved away from the app and, while I had exported some of the video, I had not had a chance to export it all, and now it seems that the app is no longer available. (The app icon is still on my iPhone, but when I click on it, I get a message that the app is no longer available in the App Store.)

Since I never actually deleted the app, I believe the video files are still on my device. In fact, if I go into 'iPhone Storage' in Settings, I see the Vee app listed and that it is using 5GB of space. I did try connecting my iPhone to my Mac and using Finder to view the files on it, but the app is not listed. Does anyone have suggestions on how I might be able to access these files? For what it's worth, the Vee for Video website is still online and I attempted to contact them (both through the email address on the website and through their domain registrar), but have yet to hear back.

iPhone Pro 15 (ios 17.3)