See https://bugs.mojang.com/browse/MCL-23290 for rationale.

This affects not only in-game but also icons, banners and other resources for game packages, such as MSIX (Windows), the Xbox website, the Xbox Game Store listing, and the Microsoft Store listings. 

https://www.xbox.com/games/minecraft-dungeons

https://www.xbox.com/games/store/minecraft-dungeons-for-windows/9p8mk4nc0ljb

https://www.microsoft.com/p/minecraft-dungeons-for-windows-launcher/9nb6bvl3mtg4

It even affects this very issue tracker. The issue tracker and website have used the new logos for the Minecraft franchise and games since the introduction of the new logos in 2021, but the issue tracker had not updated the logo for Dungeons. Edit: now see the newly opened WEB-6472

I've only included a screenshot of the in-game logo as there's too many instances to list and I do not have all of the platforms that Minecraft Dungeons is available on.