Custom nodes auto-join issue

I have two custom nodes that are of type block*, each node has a different type. Whenever I delete the paragraph between the two, they auto join although they have different node types (names). How to prevent this?

{
  "type": "doc",
  "content": [
    {
      "type": "customNode1",
      "content": [
        {
          "type": "paragraph",
          "content": [
            {
              "type": "text",
              "text": "Hello World1"
            }
          ]
        }
      ]
    },
    {
      "type": "paragraph"
    },
    {
      "type": "customNode2",
      "content": [
        {
          "type": "paragraph",
          "content": [
            {
              "type": "text",
              "text": "Hello World12"
            }
          ]
        }
      ]
    }
  ]
}

nodes:

export default Node.create({
  name: 'customNode1',
  group: 'block',
  content: 'block*',
  selectable: true,
  defining: true,
  parseHTML() {
    return [
      {
        tag: 'customNode1',
      },
    ];
  },

  renderHTML({ HTMLAttributes }) {
    return ['customNode1', mergeAttributes(HTMLAttributes), 0];
  },
  addNodeView() {
    return VueNodeViewRenderer(Component);
  },
});

thanks.

Is backspace running a ProseMirror command or the browser’s native code? I don’t think the commands in the library will do this kind of joining, so possibly you either didn’t bind a command to backspace, or none of the commands apply in the given situation and the library falls back to the native behavior.