Custom attributes are inherited when creating new paragraphs

[justYu2001]

I've extended the paragraph extension by adding a custom attribute called size to control the font size of paragraphs.

The default size is set to "large". However, when I press Enter on a paragraph that has a size other than "large", it creates a new paragraph that inherits the size from the previous paragraph instead of using the default "large" size.

Is this a bug or expected behavior? If it's expected behavior, how can I make new paragraphs always use the default size value?

The TipTap version I use is 3.0.7.

Here is my code:

import { mergeAttributes } from '@tiptap/core'
import BaseParagraph from '@tiptap/extension-paragraph'

const PARAGRAPH_SIZES = ['small', 'medium', 'large'] as const

export type ParagraphSize = (typeof PARAGRAPH_SIZES)[number]

const DEFAULT_PARAGRAPH_SIZE: ParagraphSize = 'large'

const SIZE_ATTRIBUTE_NAME = 'data-size'

export const Paragraph = BaseParagraph.extend({
  parseHTML() {
    return [
      {
        tag: 'p',
        getAttrs: (element) => ({
          size: element.getAttribute(SIZE_ATTRIBUTE_NAME)
        })
      }
    ]
  },
  addAttributes() {
    return {
      size: {
        default: DEFAULT_PARAGRAPH_SIZE,
        rendered: false
      }
    }
  },
  renderHTML({ node, HTMLAttributes }) {
    const { size } = node.attrs
    const validatedSize = isValidParagraphSize(size) ? size : DEFAULT_PARAGRAPH_SIZE

    return [
      'p',
      mergeAttributes(
        this.options.HTMLAttributes,
        {
          [SIZE_ATTRIBUTE_NAME]: validatedSize,
          style: PARAGRAPH_SIZE_STYLE_MAPPING[validatedSize]
        },
        HTMLAttributes
      ),
      0
    ]
  }
})