In the 1.16 version, trees can randomly get cut off during world gen after reloading the world, such as in the image below:

Due to this actually being a vanilla bug (MC-188086), it will not be fixed before the upcoming 1.16 release, but we are developing our own workaround for this which will come in a later release.

Please do not open any new issues related to this and keep all discussion in this thread.

For now I will be closing this as a fix has been released here.