I've updated my mod from 1.15.2 to 1.16.1, and in my mod I have a custom item drop from birch leaves. The loot table is in src/main/resources/data/minecraft/loot_tables/blocks/birch_leaves.json. This works in 1.14.4 and 1.15.2, and the loot table is valid in 1.16.1 (tested with the /loot command), but for some reason it does not override the birch leaves block loot table anymore.
Heres the loot table if that's relevant:
{
"type": "minecraft:block",
"pools": [
{
"rolls": 1,
"entries": [
{
"type": "minecraft:alternatives",
"children