>>720269549
Well yes, that's the thing being discussed. FEH often gives tit implants for Summer alts. But because Byleth's base form (and all other forms) shrunk her bust size, the "increase" for Summer only puts her at her regular size. But Rhea, who also got the increase, now dwarfs her chest.
And this was drawn by Cuboon, the earlier artist who always makes his girls into tittymonsters. And who also drew fanart of Byleth in this outfit.

3some fantasy with Rhea and Byleth.