Yes, there’s been some discussion about it in one of the hair re-pigmentation threads.
The question of is it a dye/isn’t it a dye is sort of philosophical. Here’s a few definitions of types of hair dyes that I found on Healthline:
Temporary hair colors are applied in the form of rinses, gels, mousses and sprays. These products merely sit on the surface of the hair and are washed out with the next shampoo.
Semi-permanent dyes penetrate into the hair shaft and do not rinse off with water like temporary colorings. Semi-permanent dyes usually come in liquid, gel, or aerosol forms.
Permanent dyes require more work to apply, but the hair color lasts until the new hair - “roots” - grows in. Because permanent dyes contain hydrogen peroxide, they cover gray hair more effectively and can be used to lighten hair color, unlike other dyes.
These definitions don’t seem to include compounds that are biologically active that induce changes in hair color, such as phytochemicals, amino acids, supplements, drugs or other molecules. I would argue that if you are using a biologically active compound to induce cellular changes to improve or restore the function of follicles then it’s not a dye. Yet, here’s a paper that makes a distinction of natural dyes via phytochemicals/antioxidants that improve hair color. So I suppose some people may still view such molecules applied topically as dyes. Conversely, people taking drugs orally that improve hair color (or hair regrowth) such as minoxidil or finasteride tend not to call them dyes even though the result is improved hair color.
An analogous issue is that of Tretinoin or OS-1 to for skin. Drugs (or peptides) applied to the skin improve the skin cells and the result is fewer wrinkles and better appearance. Yet, nobody argues that these compounds are makeup, which would be the equivalent to hair dyes as defined above, since makeup does nothing biologically.
Regarding GR7 specifically, in the other thread, @vblyznichenko raised the issue that the gallic acid ingredient may be acting as a dying agent since it’s used in some dyes. After a little digging, this may be the case, but it’s unclear. Here’s a patent that I found on the subject of hair dyes containing gallic acid.
On the other hand, gallic acid is a polyphenol antioxidant that is found in green tea and other natural compounds purported to be good for aging and hair color. Gallic acid may also be activating sterubin according to this paper, which was the flavanoid responsible for reduced gray hair in the yerba santa paper. So it may just be a better way of getting sterubin working than the natural extract from narrow leaf yerba santa.
