Next month USPS introduces paid tracking access (paid per delivery/request) for 3rd party apps like Parcel.
What does it mean for you if you are tracking USPS deliveries in Parcel?
If you are a subscriber, you should be able to track 3-5 deliveries per month with real-time updates.
However, if you track more than that or if you are a free (or legacy premium) user, USPS deliveries will be severely delayed for you.
More details will be available next month. USPS info:
https://postalpro.usps.com/Tracking_APIAccess_Control_Changes_Release_Overview