Legacy app stuff ,

the things is app need to target a android version like for what android version this app is compatible. 
Play store restrict apps with old targeted version like you must target android 10 at least.

but third party store have there own rules (including f-droid) and they don't always enforce these rules.

.....
if an app target android 10.0 or something older then that it will get app info as it is running on that android version for compatibility reason. 

QUERY_ALL_PACKAGES is introduced in android 11 i . so app targeting min android 11 have to follow these guideline. 

the app you are talking about is targeting android 10.

that's why //
https://bitbucket.org/oF2pks/fdroid-applications-info/src/80fe4f41219cda22922aba87f547241bee94c899/app/build.gradle#lines-10