Endwalker was a great mess(SPOILERS)

[Lauront]

If you're referring to Hyth in Amaurot, that was a shade Emet created. I might be missing something but that alone would not be inconsistent with him sacrificing himself. If they're meaning to present that whole scene as literal, then yes, it'd be a retcon of multiple sources of info, or at least it'd show her committing her betrayal way before... and at that point I just can't see how it is credible that it won't alter the future timeline.