From the email I received:
"Showing your COVID-19 status is not a requirement for entry at our first three home fixtures against Manchester United, West Ham United and Wolverhampton Wanderers - therefore, fans that cannot show their Covid-19 status for these matches will still be allowed into the stadium.
We are preparing for this situation to change in anticipation that showing your Covid-19 status might become a mandatory entry requirement, in response to government guidance."