I believe it's a memory from her past life, before she was reborn as Athanasia in this world.
You see her first life was as Athanasia, but the king killed her, so she was reborn as a korean lady, but then the korean lady died and she was reborn as her past self Athanasia again. Lucas noticed it and that's why he always says "it is not someone it is YOU." our main character wasn't reborn as some different character. She was reborn as her past self again, but doesn't rememer till now.
That mcdonald panel was her korean life self.
That's why athanasia see those "future events" or feels in some moments the "deja vu" because it already happened in her first life as Athanasia.
She lived all 3 lives first is the deceased athanasia second in south Korea as lee jihye(?) who died too and now as the current athanasia. Reread chap 98 in one panel, Lucas said smth like "looks like shes finally remembered". Conclusion, she's the real athanasia from the first time line till now
Can somebody tell me why the hell there is fast food in one of the panels? did she transmigrate from another world? didn't she just went back in time?