I sort of agree that Vader isn’t stoic and unemoting in the OT, you can see in Empire that he loses his cool by the end of the movie.

That said, though, that’s pretty much as emotional as he gets, and that’s sort of the power of scenes like this (pardon the Special Edition). You can just feel, from both David Prowse’s acting and the acting of all the Imperial Officers on the bridge with him, that he’s losing his mind with rage inside. His failure to take in Luke Skywalker has driven him past his breaking point.

But he doesn’t whip out his lightsaber tearing up some console (I don’t have any issue with Kylo as a character, but Vader is not Kylo), or cry out “Noooo!!!”, he’s pretty collected.

Nothing he does in ANH comes off as particularly hotheaded. He’s violent as hell, but not at all a hothead.

You can maintain that choking someone for disrespecting your religion is hotheaded, and in a normal society it would be. But in the high ranks of a military junta… not so much. Violence doesn’t seem as surprising to the Imperials here as it would be to us. It’s not like Vader flips out and screams at Motti and chokes him, he’s pretty collected and uses violence to prove Motti wrong. Again, which comes off as pretty normal in a despotic military dictatorship.

And you can’t say “vAdEr wAsN’t a sItH lOrD iN tHe oT, ThAt wAs A rEtCoN bY tHe PrEQuEls”

I have no idea who you’re trying to mock here, Vader having the title “Dark Lord of the Sith” was common knowledge from 1977. What exactly the Sith were was never really settled until TPM, but literally nobody would deny that he was a Sith during the OT’s production.

Honestly, I don’t really get what your point here really is at all, I really don’t think I’ve ever seen someone suggest that Vader’s completely unemoting and stoic.