I stumbled upon this in the season 15 patch notes:
" * Custom ultimate lines are now enabled for several Mythic skins, with more to come in future patches.
I haven’t found anything about this ingame though. What does it mean? Did you guys find anything concerning it?
I noticed! The unused ult voice lines for a lot of the Mythic and Legendary skins have been added!
The Moira Mythic now says
“Surrender your soul!”
and her Lilith skin now says
“Surrender to your mother!”
Sigma, Mercy, Genji, Junker Queen, Widow Maker, Orisa, Reaper, and Rein all have new ult voice lines when using their Mystic skins now!
Kiri, Ash, Hanzo, and Ana still use their old ones! Also Ramattra’s poseidon skin does says “SUBMERGE, AS I HAVE!”
There could be more but this is all I found so far<3!
Thank you!! I dont want to unequip Ducky Mercy, but i really need to try her mythic later