My little observation.
If you look closely, then there are five hands with flowers to Petra, whose number corresponds to the members of the Levi squad (Eren, Gunther, Erd, Oruo, Levi) Next to Petra there are two hands depicted, it can be Levi and Eren, or even Levi and Oruo. Since these two men are closest to Petra. I don't know much about colors and maybe people who do will come up with their own headcanons. But it seems to me that the roses may belong to Levi (And this is even without any hint of rivetra), he is the one who could give roses, since he, being the captain, has more money to buy these flowers.
In any case, this is nothing more than my theory. But I still wanted to share it.












