Hi there!
YunoHost 11.1 was released almost one year ago, introducing the “version 2” format for app packaging, meant to simplify various packaging aspects, get rid of historic and inconsistent quirks, and improve user experience.
Since then, more than 75% of the catalog is now using packaging v2 ! 
… with many other ongoing pull requests to convert the remaining apps.
As a consequence, the app linter will now yield a warning for packaging-v1 apps starting on February 1st, 2024. This doesn’t change much the status quo, except that existing packaging-v1 apps won’t be able to reach level 8 anymore on CI and will be capped to level 6.
In one year from now, on February 1st, 2025, these warnings will turn into errors, meaning that the corresponding apps will be capped to level 4, meaning they will be flagged as “low quality / broken”, won’t be shown in the catalog by default, and YunoHost’s diagnosis will report an error about existing installs.
Finally, while YunoHost 12/Bookworm is not even out yet, we are already planning to completely remove support for v1 packaging for YunoHost 13/Trixie. By that time, we will surely have started working on packaging v3 !