Ki-Adi-Mundi’s birth was never actually stated in canon, it’s also worth mentioning that this is one of the more minor changes from Legends to canon so I’m honestly surprised people are upset about his cameo compared to more major ones.
To comment on your claim that his quote from The Phantom Menace contradicts his appearance here, I’d have to disagree: We still don’t know if the masked character is actually a Sith yet.
I didn’t care for this episode either so I’m not defending this show btw