/ubl:Invoice/cac:AllowanceCharge[cbc:ChargeIndicator = true()] | /cn:CreditNote/cac:AllowanceCharge[cbc:ChargeIndicator = true()][BR-37]-Each Document level charge (BG-21) shall have a Document level charge VAT category code (BT-102).
Hitting this rule in production? Paste the invoice into the validator or wire the API into CI so it never ships broken again.