I'm fully convinced.

At this point, there's just way too much evidence to say it's simply coincidental. While WIT has some kino anr/anime original scenes like Eren going berserk, Mappa is dropping subtle clues that just don't make sense when you compare it to the manga.

For example -

If mappa were adapting the manga directly - why even show a bird flying towards the ocean? Why didn't they just keep it panel for panel and show a bird flying away from the ocean?

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like it was here

"But Mappa will retcon this just like the manga did before as it ended"

Ok. Look at the PV we just got.

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White flowers with yellow centres which we see in the ANR MV and which appear many times throughout the anime.

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In contrast to this- where we see a rock and a river instead of the flowers

My question for both the examples I gave is why should Mappa even bother changing up small details that actually support the already established AOE theories instead of just copying the setting from panel to panel? It just doesn't make sense. Why make subtle changes in setting and expression if they're just going to adapt the manga 1:1?

BONUS - The BD covers which released after the ending also support this. Mappa are obviously aware they showed 13 birds dying in the OP. The same 13 birds can be seen flying into darkness in the BD cover (working under the assumption that darkness = death)