Reviewers comments refer to last (senior) author
It is not uncommon. Reviewers must be aware of your professor's previous work and therefore, they refer to this work as Professor D et al. though you are the first author (A). However, if the reviewer is publishing his/her own paper, he/she will refer to this paper as A et al.
I have received comments like this the following &quot;In this work, D et al. have confirmed the hypothesis they had proposed in the previous work of D et al. (J. Basket weaving, 2016).&quot;
In any case, there is nothing to worry about. Reviewer's comments are meant to improve your paper and don't reflect on the work done by A versus work done by D.