My mother who died at 89 in 2015 was pulled out of Catholic school by her very Catholic mother (big Irish Catholic family, the whole nine yards) in the 1930s and sent to the public school thereafter, because she was being emotionally abused by her teacher, a religious sister. My mother had a rather jaundiced view of religious sisters generally for the rest of her life, although there were one or two sisters she really liked (one was my fifth grade teacher) and became good friends with.
Mother Angelica also had some not-very-nice things to say about her time at Catholic school when she was young.
I am sure there were some sisters who were very kind and good teachers, and others who were not. I had the same kind of “mixed bag” experiences with them when I was young. There are some I remember very fondly and others not so much.