How to check open source?

Question

Programming

I'm not a programmer myself, so the interest is purely academic.
There are open source projects. For example Telegram or Tor. Or something else. It is assumed that the code does not contain backdoors, obvious errors and other garbage. anyone can research it and report it to developers or users. But is there any guarantee that the directly downloaded application/program/etc is built from these open source codes and not some others? How is it checked?

Answer 1

If this is important to someone, then they themselves collect from the source. It is impossible to give guarantees, in addition to the reputation of the one who collects.
The only guarantees that you can get is that you downloaded the very one that was posted by the developer.