Apple updated approach it provides for subscription grace periods. Duration of grace period is not could be set manually (previously it was hardcoded for each subscription duration).
Billing grace period could be existing paid renewals or all subscription renewals (existing paid renewals and free offers transitioning to paid renewals).
Apple Developer: App Store Connect Update
Developer:Check the billing grace period configuration.
QA engineer:Update test cases for various grace periods.
PM/DM:Communicate feature availability. Update billing grace periods, if needed by business.