“Additionally non-frum Jews aren’t protected as frum Jews are by Jewish law. For many protections they fall under the same category as gentiles.”
“If someone regularly drives in public on Shabbos or regularly eats cheeseburgers and non-kosher without shame, he’s publicly known to be not frum.”
“However, one who sins out of ignorance or temptation is in the category of amecha and it is forbidden to speak loshon hora about him” (Chofetz Chaim, A Lesson A day by Rav Shimon Finkelman and Rav Yitzchak Berkowitz, Day 14).
Nearly all (if not all) not-Frum Jews today fall under this category.