The 2x2 Surrounding Saplings fix for [MC-8187] allows 2x2 saplings such as spruce, jungle and dark oak to grow even when completely surrounded on all 4 sides.
Simple, it fixes an offset in TreeFeature.getTopPosition that makes 2x2 trees check a 3x3 area at the trunk, catching additional blocks that don't determine how the tree should grow.
Simply install [Fabric] or [Quilt] for Minecraft 1.16 and newer, then install this mod.
Theoretically, 2x2 trees may spawn more frequently in a given world, and old builds not expecting 2x2 saplings to grow may suddenly get a surprise.
Any modded trees that are 3x3 may also erroneously check for a 2x2 trunk if it relies on the generator to filter out whether a space is valid.

Fixes MC-8187, allowing 2x2 saplings such as spruce, jungle and dark oak to grow even when completely surrounded on all 4 sides.