custom-post-type and post-carousel custom attributes

Hello,
I’m trying to add a custom attribute to getwid/custom-post-type and getwid/post-carousel using blocks.registerBlockType:

const blocksWithSubpageLink = [ 'getwid/custom-post-type', 'getwid/post-carousel' ];

function formatsSubpageAttribute(settings, name) {
  if (typeof settings.attributes !== 'undefined') {
    if ( blocksWithSubpageLink.includes( name ) || hasBlockSupport( name, 'formatsSubpage' ) ) {
      settings.attributes = Object.assign(settings.attributes, {
        showSubpageLink: {
          type: 'boolean',
          default: false
        }
      });
      // console.log(settings.attributes)
    }
  }
  return settings;
}

addFilter(
  'blocks.registerBlockType',
  's24/brand-formats-subpage',
  formatsSubpageAttribute
);

If that attribute has a value (even the default one) the block rendering fails.
Console error:
Failed to load resource: the server responded with a status of 400 (Bad Request)

It seems that custom attribute are forbidden, perhaps for some data validation.

Do you have any suggestions or ideas?
Thanh you!