minecraft-bedrock-json-schemas/source/behavior/blocks/format/components/immovable.json

{
  "$id": "blockception.minecraft.behavior.blocks.1.17.0.minecraft.immovable",
  "additionalProperties": false,
  "type": "boolean",
  "title": "Immovable 1.17.0",
  "description": "An Immovable block cannot be pushed by pistons"
}