Why Do I Refer to the Author of Hebrews As "She"?

We don't know who wrote the Epistle to the Hebrews. It slid into the New Testament canon because it got categorized as a letter of Paul (though there were plenty of doubters of that as well). But the use of Greek, style, and literary composition is quite different. And it would be unusual for a letter not to be signed.

My favorite theory is that it was authored by Priscilla, of the New Testament couple Priscilla and Aquila. The article linked goes into pretty great detail as to why this is an acceptable theory. But, in brief, what we know is:

1. Priscilla was a big deal in the early church.
2. There is evidence in the 2nd century and beyond of the suppression of Priscilla's involvement in the early church (for instance, switching the order of Priscilla and Aquila's names, so that Aquila was listed first); as well as the suppression of women's involvement in general.
3. There's evidence within the book itself; for instance the author's pronoun use going back and forth between "I" and "we" (so perhaps written by a couple); the use of women and suppression of men in Hebrews 11; the elevation of other feminine issues.
4. Just the fact that she's just as obvious a candidate as any other theory put out there—Apollos, Timothy, Barnabas. Why not include women in the list as well? Phoebe, Junia, Mary. So many women in the New Testament to choose from.

https://www.cbeinternational.org/resource/priscilla-author-epistle-hebrews/