Islam has had negative effects on Persian people in several ways, including:
Persecution of Zoroastrians
After the rise of Islam in the 7th century CE, Zoroastrians were persecuted on a large scale. This included forced conversions and violence.
The Islamic Republic of Iran has been accused of human rights abuses, including:
Enforced disappearances
Torture and other ill-treatment
Systemic discrimination and violence against women, girls, LGBTI people, and ethnic and religious minorities
Cruel and inhuman punishments, including flogging
Punishing activists and religious and ethnic minorities for peaceful activities
Preventing the free exercise of belief and expression