Well after I chop down the wood of a tree and the leaves start to decay, the first leaves decay really fast like the datapack is supposed to, but nearing the end of the leaves decaying it slows down and there's always a bit of leaves that stay and take a while to decay. Especially on larger trees where there are more leaves, it takes a while for all of them to decay. It may just be lag on my end but I'm not sure.