The US government / CIA did in fact develop the protocol back in the day, with the goal of helping people in China and other countries message securely, probably with ulterior motives.
But the protocol itself is open source, and you can use it without any affiliation with the US government.
The claim " It looks almost as if big tech in the US is not allowed to build its own encryption protocols that would be independent of government interference 🐕🦺" is therefore so stupid it almost invalidates everything else being said because the person writing is either an idiot or purposely misrepresenting the facts.
Not having reproducible builds is definitely weird though. Does anybody have more information on that?