Kind of obvious that isn't it?
Anyway, more info from the club https://www.brightonandhovealbion.com/news/2205181/important-advice-for-anyone-attending-the-amex-this-season
https://www.theargus.co.uk/sport/19488168.brighton-fans-face-new-covid-measures-enter-amex/
According to the Argus it must be a photographic ID, so birth certificates are no good.