TAX COMPUTATION AND ITR

One assesse a partnership firm filed their income tax return for the AY 19-20 U/S 44AD in ITR-4 , but during the A Y 20-21 they are not opted Section 44AD and filed return in ITR 5, No Tax audit done . Just paid Income tax on the net profit which was less than the presumptive income to be offered  . What are the consequence will come for not opting presumptive taxation  during the A.Y 20-21 and what stand they have to take in A. Y 21-22. Whether they have to select 44AD or to go for 44AB for the A.Y 2021-22. please guide