Now, did individual priests and nuns discourage Bible reading *on their own authority* even after that time? Quite possibly.
Agreed. Have never heard it referred to as “a sin”, just something they preferred you let them do for you.
And yes, you will encounter individual Nuns and Priests who believe all sorts of wacky things.
In Catholic school in the 50’s and 60’s (both elementary & high school) we were told not to read the Bible but to only study our catechism by both the nuns and priests.