For the UK customers only:
Due to the UK leaving the European Union on the 1st of January 2021, the delivery time of your item can be delayed due to the new custom processes at the UK border.
Also, most of the items are now produced and delivered from the US.
Apart of the Brexit problems for the UK customers, your item can be delay due to the pandemic. The delay can be on production or a any other issue related to the pandemic in terms of logistics.