As of 1.16, hoes are now the preferred tool for breaking leaves. As such, axe leaf harvesting should be deprecated.

I really enjoyed this feature in older versions of quark. Maybe it could be introduced in quark oddities or brought back but be disabled by default? Or maybe there is a mod that adds just this feature?

How exactly do you "deprecate" a feature of a mod? I think removing it would make sense, but it doesn't really make sense to say "you can do this but it's not reccomended and you shoud do this instead, the old way will get removed soon" with a feature of a game.

I like the feature.