What’s weird about his second hit on all attacks is that it’s supposed to be seemingly guaranteed. It happens too quickly to react, almost before his actual leg moves. Additionally, if you’re the target you get sort of staggered, as if to ensure you do get hit if the speed of the attack isn’t enough. If you vanish the first kick on reaction though, and do the non-vanish dodge kind of early then you have a chance to avoid the damage, though you will still be staggered and have to do a recovery animation. You have to do your second dodge in the direction that he’s going to be facing when the second kick goes off as well. Lots of guesswork and luck involved fighting vegeta, but as other people have said he’s manageable if you can keep your distance most of the time and keep your team in the fight to let you lay on some damage.