It didn’t feel out of character of the Vader we see in Revenge of the Sith who cut down younglings. It doesn’t fit Vader in the original film though.
I mean its a sequel to Revenge of the Sith. It even has Jimmy Smits and prequel Mon Mothma Genevieve O’Reilly.
Both of them will be in the Andor and Kenobi series which connects the main story even further.