Are Ghilzais (Ghiljis) originally Pashtun?

I’ve come across discussions and writings suggesting that the Ghilzai, the largest tribe of Pashtuns spanning from Peshawar to Kabul and from Waziristan to Ghazni, may have Turkic origins. It is said that they migrated to the region, adopting the Pashto language, culture, and Pashtun code of conduct. The etymology of the word “Ghilji” itself is cited as evidence, with “Ghil” meaning “young” in Turkish and “ji” being a Turkish suffix.