Just a thought why COVID may be impacting so many folks. My local post office tells me the protocol they have been asked to follow for screening employees creates real staffing problems. I may not have all the details right, but this is my current understanding.
Each day each employee must be screened. They check several 'symptoms', including temperature. As an example, if a person has an elevated temperature, they are not allowed to report to work. They are sent home. If temperature remains elevated for two more days, they are asked to see a physician and get a COVID test with results coming back in 1-2 days. So at a minimum, a high temperature and a negative COVID test would keep the person out of work for 3-4 days. If they have been exposed to a person with COVID, they have to self quarantine for two weeks and have a negative COVID test before being allowed to come back to work.
There are several other elements, but I think you get the idea. Local postmaster tells me in late 2020 they were trying to run the business with 35-40% of the staff out due to failed screening. Since the first of the new year, things have improved. Now, the typical shift staffing is down about 20%.
First class mail is top priority. Packages, regardless of shipping method are lowest priority. So the 'new' normal really does mess up shipments. The 'old' normal may not be back until early Summer. I suspect similar issues are impacting UPS and FedEx.