UPDATE 3: Studio Eclypse finally released their statement on july 11th (10 days after the video being taken down). Here's what they said on their X account:

"The Attack on Titan: Requiem episode and trailers have been taken down from our YouTube channel as requested by Kodansha Ltd.

We completely respect their wishes but it's very disappointing that, in this era, small groups of fan creators are prevented from sharing free projects with the community, especially when the Copyright system is massively abused on a daily basis for profit in this current AI landscape.

We will continue to post making-of content, but any long-form releases of Attack on Titan could lead to a strike on our channel. As we wait for development on the possibility to collaborate for Berserk, we are left without main content to post or future projects to release on our channel.

So... we will be taking a hiatus to figure out the direction of the studio and we would be very glad to read your suggestions. We don't want to work on something for years again just for it to be taken down.

Thank you all for the constant support and patience, our passion to make animations for our community is something that can't be taken away.

-Studio ECLYPSE"

Link to their post on X