The EFL site has updated the list of referees for 2021/22.
The changes are those that we are already aware of. No longer listed are Duncan, Mason and G Salisbury. The additions are Kitchen, Mather, Reeves and Welch.
https://www.efl.com/clubs-and-competitions/match-officials/national-list-of-referees/
No assistants listed as yet but it looks like that page is work in progress.
Having seen Mark Jones on the line at Spotland on Friday and looking at his other appointments this season, it would appear he is no longer a SG2 assistant.