Linked to this issue seems to be that F-Droid is misleading users about what is labeled as a "reproducible build", comparing it to their own builds instead of the app developer's builds.
To quote the developer in the linked GitHub issue:
You now have a "reproducible build" by your definition, because you confirmed your own result. But have you confirmed a match with the source code? I don't think so. At best, you have confirmed your tooling consistently has it wrong. And that is exactly why F-Droid's definition of a reproducible build is so weak: I have to trust you saying your version is correct, instead of you trying to match your version with mine to ensure we both got the same result, which would create 2 parties confirming each other's results.