Although it says in the statement that is was for their 2021-2022 FY (signed in August), in the UK home office modern slavery registry is says: 

The statement covers the following period:

1 May 2020 to 30 April 2021

The statement was signed off by:
Dale Vince (Director)

It was approved by the board (or equivalent management body) on:
9 December 2021