USPS OIG: Does First Class Mail Get First Class Service?
"We found significant declines in First-Class Mail performance nationally with the onset of the COVID-19 pandemic. Service performance at the 17 selected districts trended comparably but with lower scores. What contributed to the decline? A flood of packages into the network, combined with low availability of experienced employees overloaded many plants. Other mail processing and transportation constraints didn’t help, and some mail facilities had to use resources to offload mail to alternative plants."