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