i havent chopped down a giant spruce in a while, so i dont know if this issue goes back further, but i planted three giant spruces and when i cut them down, as soon as there are leaves on the tree, its all leaves.  Instead of being a 2x2 area of logs, there's just a 1x1 and its every other block is a log, the rest is leaves. this happened on all three trees, and then with newly planted ones after that.

The first set grew naturally, the second set were bone mealed

In the screenshot i have cleared out the leaves