I have checked the "MR !11" working fine with the field type "managed_file".
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I have checked the "MR !11" working fine with the field type "managed_file".

Please check the below steps:

1. Install and enable the Menu Link Attributes module.
2. Go to the configuration page "/admin/config/menu_link_attributes/config".
3. Add the "managed_file" field as per the below code:
   icon-attr: label: 'icon label' type: managed_file upload_location: 'public://module-images/menu-link-images/' file_validate_extensions: 'gif png'

The "file_validate_extensions" key was added to the patch. so we can restrict the file with different extensions.
Please check the after image.

It will not allow a jpg file.

It will allow only png and gif files.