Some trees are generated with a "cut"... Looks like some generation bug, see the screenshots below.
The world has been created with 1.13.
Seed and coordinates are in the screenshots.
Environment
Mac OS X 1.12.6
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)
Sometimes trees will spawn with dirt and stone as leaves. and fire acts weird with tree's as well.