I heard a Shiur from Rav Schachter where he said that a Mashgiach technically only loses his ne’emanus if he violates the Halachos of Kashrus or is a Mumar l’Kol HaTorah (i.e. Mechalel Shabbos). If he is guilty of other Avairos, no matter how severe, he is not automatically disqualified. Thank being said, you would not necessarily want him as your Mashgiach.
BTW, a shochet working for one of the lessreputablee hechsherim once told me thelocationn he worked had 7 shochtim who were Shomer Shabbos and 6 who weren’t. the Rav HaMachshir said, “Better to eat Neveilos than Treifos”