For the past year (since covid) now I spend time answering emails from customers asking where their order is. These are all USPS orders. Just this week alone, five inquiries - mainly orders that were shipped three weeks ago. USPS tracking indicates "In Transit." In the past eleven years I have never seen such a train wreck as USPS currently is.
Yes, covid has increased the volume shipping USPS since more people are ordering online than ever before. Yes, USPS has had employees out with covid so that is a challenge for them. And yes, if it were a private company they would have adjusted after a month or two. But USPS is a pseudo governmental agency that is lumbering at best. There are great people who work there but the organization has literally been unresponsive. Our experience is that USPS has gotten worse in the past six months, not better.
My understanding is that USPS doesn't fly their own mail around anymore. Fedex flies all of the Priority mail and 1st class mail is now walking (a USPS "reform").