Which you a) don't even have to do https://signal.org/android/apk/ b) can pull from your phone to compare the apk hash against reproducibly built client.

Open source is not panacea, but it's a requirement for verifiable security.

So how about you show us that either the play store APK doesn't match, or, that the source has the backdoor you claim it has.

If Signal had a backdoor a proof of it would have surfaced by now. There have been many cases where law enforcement repeatedly fail to get any useful information whatsoever from the Signal Foundation because they have nothing to offer and simply cannot obtain any useful evidence.

Signal having an "obvious" backdoor is really a thing for the tinfoilers, crackpots, and the misinformed.