How early are you/have you sent parcels to other parts of the UK for Christmas?
The Royal Mail site says last posting date for 1st class is December 21st and 2nd is the 18th but that seems VERY tight to me! Covid seems to have slowed everything right down, plus obviously Christmas coming up and the fact that a lot more people are doing their Christmas shopping all online this year.
Have you sent/received things late recently? Or within the expected timeframe?