square.onMerchantCustomAttributeVisibleDeleted subscribes to merchant.custom_attribute.visible.deleted for the selected seller. It requires MERCHANT_PROFILE_READ.
Example
automations/square-on-merchant-custom-attribute-visible-deleted.automation.ts
Event
A custom attribute that’s visible to your application was deleted from a merchant. The signal resolves to the officialSquare.MerchantCustomAttributeVisibleDeletedEvent payload with type narrowed to merchant.custom_attribute.visible.deleted.