In 1.18 Pre-release 1, the Cave Surface decorator was removed and replaced with a specialized configuration of Environment Scan. However, the configuration used is incorrect in some cases and does not accurately replicate the old logic.

The Bug

As shown in the spore_blossom placed_feature:

{
      "direction_of_search": "up",
      "target_condition": {
        "type": "minecraft:solid"
      },
      "allowed_search_condition": {
        "blocks": [
          "minecraft:air"
        ],
        "type": "minecraft:matching_blocks"
      },
      "max_steps": 12,
      "type": "minecraft:environment_scan"
    },

The Solid predicate checks that the block to place in is a solid block. Since the loop ends and generates the feature when a solid block is found, the feature generates inside the block instead of below (or above) it. This affects spore blossoms, cave vines, and pointed dripstones and causes them to generate incorrectly.

To reproduce
Load the seed -7899173361933028793 and run /tp 58 36 314. Observe the incorrect spore blossom and cave vine.

Solution

Either an offset config should be added for the Solid predicate (to enable checking one block above or below), or a random_offset with a y offset of 1 or -1 should be added onto the end of the feature to compensate for the solid check.