They certainly should have made an agreement like that before the season started, and formalised it the rues and regulations for the season (and included those conditions in the TV deal). It would be the only sensible thing to have done.
But have they?
Don’t think so - rules require a board meeting to decide on how things will be determined. I guess there are too many variable for them to cover every eventuality in advance.
Page 105 onwards
https://resources.premierleague.com...f-3d9d6696ac6f/2020-21-PL-Handbook-031220.pdf