I can't speak to that with a familiar level with the code, I can only presume or guess. All I will say is that is why I never install any app from Github or Gitlabs, because there is no third party verification of the code for releases on those sites.
I only use F-Droid after disabling all anti-features in Settings and then install apps that I know are 100% clean from all dependancies.
Download the SimpleX apk from F-Droid website and then run that to see what it says for any difference in the results.
It's too bad that the F-Droid releases are far behind. I do not install from Github to prevent against proprietary dependancies.