I didn't like Pitt's performance either. Pitt's a charismatic actor, and I didn't feel he was able to capture the quiet, emotionally stunted nature of his character in the same way that, say, Ryan Gosling did in First Man. Redlettermedia, in their review for Phantom Menace, made this exact point about Sam Jackson in his role as Mace Windu(I think?). Sam Jackson isn't a stoic Jedi, he's a charismatic badass! Pitt isn't necessarily a badass (though he can be), but I thought it was a mistake casting him.
I'm sure someone will correct me if I'm wrong, but wasn't Harvey Keitel initially intended for the role of Willard in Apocalypse Now? And then Coppola went for Martin Sheen because he had a natural reserve where Keitel has a kinetic energy? Factually incorrect or not, this is how I felt about Pitt in Ad Astra. I just couldn't take to him at all.
Nor could I take to the VO, which felt too self-consciously philosophical. Tommy Lee Jones was great, though, when he eventually turned up. Some of the close ups on his face said more than any of the VO.