Hi there!
Thanks for reaching out.
The asset.uploadCustomIcon endpoint has been secured in the latest SP Page Builder v6.6.2.
If you've already updated to SP Page Builder 6.6.2, performed a thorough security check of your website, and ensured your site is protected with appropriate security measures, you can safely ignore these blocked requests. They are most likely automated attempts to exploit known vulnerabilities on publicly accessible websites.
If you haven't updated yet, we strongly recommend upgrading to SP Page Builder 6.6.2 as soon as possible and taking a full backup before performing the update.
Best regards,