Pasting in block results in pasting the content twice in Firefox

[khnn]

Describe the Bug.

When pasting text from the clipboard to a custom block into the lexical editor the text is pasted twice. I only experienced that in Firefox.

pasting_ff.mov

Reproduction Steps

• Create a payload app via CLI
• Use the website template
• Add a custom block to the existing BlocksFeature in the post's collection like this

// src/collections/Posts/index.ts

..
export const ContactBlock: Block = {
  slug: "contact",
  fields: [
    {
      name: "first",
      label: "first line",
      required: true,
      type: "text",
      admin: {
        description:
          "...",
      },
    },
    {
      name: "two",
      label: "second line",
      required: true,
      type: "text",
      admin: {
        description:
          "...",
      },
    },
  ],
  interfaceName: "ContactBlock",
};
...
BlocksFeature({ blocks: [Banner, Code, MediaBlock, ContactBlock] }),
...

• Add the new block to the editor
• Copy some text (I used Apple Notes and other sources to copy from)
• Paste it in the first text field
• The text is appearing in the field and another time under the block (see video)

Environment Info

Payload: 3.17.1
Next: 15.1.4
Node: v20.17.0
Firefox: 134.0.1 (aarch64)