The "new" Taliban considered her an unbeliever for appearing unveiled and, apparently, rejecting their authority.

“When you meet the unbelievers, strike necks…” (Qur’an 47:4)

“Taliban behead junior volleyball player who was part of Afghan women’s national team:

Report,” IndiaToday, October 20, 2021

Taliban militants allegedly beheaded a member of the Afghan junior women’s national volleyball team, a coach told the Persian Independent.

In an interview, coach Suraya Afzali (name changed) said a woman player named Mahjabin Hakimi was killed by the Taliban earlier in October, but nobody learnt about the gruesome murder as the insurgents had threatened her family not to talk about it.

Mahjabin played for the Kabul Municipality Volleyball Club before the collapse of the Ashraf Ghani government, and was one of the club’s star players. Then, a few days ago, pictures of what seemed to be her severed head and bloodied neck turned up on social media.