craftbukkit/nms-patches/net/minecraft/world/level/block/VegetationBlock.patch

--- a/net/minecraft/world/level/block/VegetationBlock.java
+++ b/net/minecraft/world/level/block/VegetationBlock.java
@@ -12,6 +12,10 @@
 import net.minecraft.world.level.block.state.IBlockData;
 import net.minecraft.world.level.pathfinder.PathMode;
 
+// CraftBukkit start
+import net.minecraft.world.level.World;
+// CraftBukkit end
+
 public abstract class VegetationBlock extends Block {
 
     protected VegetationBlock(BlockBase.Info blockbase_info) {
@@ -27,7 +31,15 @@
 
     @Override
     protected IBlockData updateShape(IBlockData iblockdata, IWorldReader iworldreader, ScheduledTickAccess scheduledtickaccess, BlockPosition blockposition, EnumDirection enumdirection, BlockPosition blockposition1, IBlockData iblockdata1, RandomSource randomsource) {
-        return !iblockdata.canSurvive(iworldreader, blockposition) ? Blocks.AIR.defaultBlockState() : super.updateShape(iblockdata, iworldreader, scheduledtickaccess, blockposition, enumdirection, blockposition1, iblockdata1, randomsource);
+        // CraftBukkit start
+        if (!iblockdata.canSurvive(iworldreader, blockposition)) {
+            // Suppress during worldgen
+            if (!(iworldreader instanceof World world) || !org.bukkit.craftbukkit.event.CraftEventFactory.callBlockPhysicsEvent(world, blockposition).isCancelled()) {
+                return Blocks.AIR.defaultBlockState();
+            }
+        }
+        return super.updateShape(iblockdata, iworldreader, scheduledtickaccess, blockposition, enumdirection, blockposition1, iblockdata1, randomsource);
+        // CraftBukkit end
     }
 
     @Override