That muzzle makes her look like a G1 pony.

They zoomed in on her eyes for a reason. It’s to hint at who she is. So she has blue eyes which means that she could be a number of ponies of import that we’ve seen. (Going from the show and not the comics)
Alicorns: Luna has blue eyes, flurry heart (Strong Chance)
Unicorns: Rarity, maybe princess platinum?
Pegasi: None really
Earth Ponies: Diamond Tiara, Pinkie pie (Doubt),
Changeling: Maybe Chrysalis but doubtful
Kirin: None

Out of these, I think that Flurry is the most likely with Luna coming in second and Diamond Tiara coming in third. Ignoring the comics, Flurry heart is the most likely because of the association with crystal and crystal related magic. I don’t think it’s Luna because I doubt that they would write her to be evil again. It could be Diamond Tiara but I think they did her dirty enough already by not mentioning her properly since season 5 of g4. I don’t think DT has it in her to chase alicornhood ambitions either. As for Princess Platinum, that would be interesting but I personally doubt it.

It could also be an original character. Where would a new alicorn come from if not from outside of Equestria? We would have heard of this alicorn before if they were from the nation of Equestria. I’ve heard that she is an “asian” pony because of the curved horn but I don’t know if that lies within or outside of Equestria as we know it. Kirin horns are bulkier and she lacks Kirin features so she is not a Kirin. She could be from another crystal “Empire” that recently emerged from stasis like the crystal empire did in season 3 meaning she might have connections to Sombra which is where Sombra might come in since he was mentioned in the toy line.

@Naftazol
Maybe Twilight Sparkle’s and Cozy Glow’s grandchildren made her. ;D

@Background Pony #9116
She clearly isn’t Twilight Sparkle, take your awful fanfic idea somewhere else.

intresting

Twilight Sparkle after becoming corrupted….