What technique is used. To create the shaded areas in Goya’s print asta su abuleo

Printmaking.

Explanation:

After some research, I went to https://artmuseum.princeton.edu/collections/objects/5480

and in the medium section, it showed  aquatint.

According to Wikipedia, "Aquatint is an intaglio printmaking technique, a variant of etching that produces areas of tone rather than lines. For this reason it has mostly been used in conjunction with etching, to give both lines and shaded tone."

this is a good question! i'll do some research and come back when i have the answer!