Vatican II changed the expression of the “faith” . You are correct that the True Magisterium of the Faith has never and will never change. But the changing of the True Sacrifice of the Mass into a Protestant commemoration, with no option for the True Mass, drove people from the churches in confusion. I was one of them, baptized in 1960, first Communion in 1968, then everything changed. I didn’t know what to think, we went from the solemn High Mass incensing of the altar to the guitar Mass and Kumbaya. God brought me back to the true Church in my 40s when I discovered there was another option, the SSPX and other traditional groups who were perpetuating what I thought was lost.