Not open source, which is a red flag for me. There are QR scanner&generator apps on F-Droid, and you can check the source code that they do NOT send the scan result to some server and do NOT sneakily take a pic of you with the front camera.

Here is what you should do for security around QR codes.

In cases when privacy isn’t important (here, Google can match my Google and Lemmy usernames, and I leave a public comment), you can use Google Lens (in browser!) and crop the area of focus, and it works for QR codes on bent surfaces.