Apple Pay on the Web Merchant Validation Intermittent 403 Forbidden

We are experiencing intermittent 403 Forbidden errors during Apple Pay on web merchant validation in our production and sandbox environment.

1. Has anyone else started seeing 403 Forbidden errors recently (since mid-2025)?
2. Why would merchant validation be sometimes successful and sometimes fail with 403?
3. Could this be related to new Apple Pay gateway changes or stricter validation rules?
4. Any additional debug steps or permanent solutions we should try?

Thank you.