#skrulls

No, but I'm not surprised this theory exists. I'd ask why they think he's "acting weird" but I've seen most of those posts already.

Its either

"Why is he so sad? This is ooc because he was happy in the final scene of The Falcon and the Winter Soldier" The answer to that one is simple: he has depression. Depression doesn't disappear no matter how hard that show tried to sell us the idea that Bucky was totally "cured". In Thunderbolts he's having a "low" point after the "high" in The Falcon and the Winter Soldier. Since the movie is about depression that fits perfectly. .

"He betrayed Sam by making his own team?" The idea that Bucky creating his own team is a "betrayal" of Sam is ludicrous, and adopting a band of misfits is the single most in character thing Bucky could do. I mean did everyone just forget how he adopted Steve Rogers when he was a skinny, weak little punk? Adopting misfits and taking in feral cats has always beeen his thing.

If its about the Congress thing Sebastian Stan already explained that.

Also the Skrull thing has bascically been abandoned in the MCU now after Secret Invasion wasn't well recieved. As per that show the characters that we absolutely know were replaced with Skrulls were Nick Fury, Rhodey and Everett Ross.