in recent weeks, as a budget move (or to compel Congress to act) the Postmaster General has issued orders that overtime is out, and mail will have to sit an additional day. This could represent multiple days because it could happen potentially at each stage of its path.
In addition, there are COVID-19 concerns (with sick employees), and mail is not generally been sent via airplanes during the pandemic.
I send a couple packages a day, and receive one a week. I have generally found that 2-3 shipments are now taking 8-21 days (domestic).