ITR 44AD

It depends on the reason why it was not opted during ay20-21 or rather why no return was filed. If it was not opted because the turnover was more than the limit or if the income is within the basic exemption limit, then yes, you can opt for it again, I think.

As per my understanding, sub-section (4) is applicable only when the assessee does not declare profit in subsequent years as per sub-section (1) despite being an eligible assessee.

Is it like this?