Agree to wait a day or two, but there should not be a need to calculate any spend Band as those fell away during lock down period,The cash back %'s are almost always all over the place on the first one or two days of each month, wait a while for it to settle.
It is not really possible for them to determine the spend band of the previous month this early as some transaction (transacted on, by example, on the 29th or 30th) still needs to clear.
So it's based in your card type and money status which should just tick over from last month
But yes will wait