Yes, it’s a bug.
There have been a few new releases of the QuickBooks app, since IOS 13 came out, but it’s not fixed yet. I think it’s linked to Apple changing the location of the camera roll.
The original bug let you tap on a photo, but the button to say “use this photo” (I forget the exact wording) wasn’t there, so you were left hung looking at the photo and had to force quite the app.
I’m now on Version 19.10.0, which has removed the option of adding a previously taken photo entirely. The options now are “take photo” (and the camera pops up, you take a picture, click use this photo) which works. Or, there is a “browse” option, which allows you to view files on your phone, but nothing from the “photos/albums” storage.