I didn't know this until yesterday. After 5 October Premier League teams will be able to deal with EFL teams only and not with other Premier League teams until 16 October? Think that's right?
Taken from the Premier League site :
The summer 2020 transfer window is open from 27 July to 23:00 BST on 5 October.
A domestic-only window, during which Premier League clubs can trade only with those in the EFL or below, will run from 23:01 BST on 5 October to 17:00 BST on 16 October.
The deals, loan or permanent, announced by clubs below may still be subject to international clearance and/or administrative details before they can be confirmed.