In 2004 a large part of the Orthodox sheitel market collapsed within weeks, and the reason was a question about where the hair came from.
Much of the human hair used in high quality wigs was sourced from India, and a substantial part of the Indian supply comes from temple tonsure, where pilgrims shave their heads as an offering, most famously at Tirumala Tirupati. The temples sell the hair at auction, and it enters the international trade.
The halakhic question is whether hair given as an offering at a temple to another deity counts as an object of avodah zarah, idolatrous worship, from which no benefit may be derived. Several senior authorities in Israel, including Rabbi Yosef Shalom Elyashiv, ruled that it did. The consequence was immediate: women were instructed not to wear wigs of uncertain provenance, wigs were destroyed publicly in Brooklyn and in Bnei Brak, prices for European and synthetic hair rose sharply, and a certification system for wig provenance came into being that still operates.
Other authorities disagreed, arguing that the tonsure is a hygienic and votive act rather than an offering to an image, or that the hair is not the object of worship, or that the chain of commerce interposes enough steps. The dispute has not been resolved so much as absorbed into a market where certified non Indian hair is now standard at the strict end.
The episode sits alongside the older objection to the sheitel itself, made by some Sephardi authorities and by figures including Rabbi Ovadia Yosef, that a covering indistinguishable from uncovered hair does not achieve what covering is for. Communities that take that position prefer a scarf, and the two objections come from opposite directions.