Specifically for the Chef one: His voice actor, Isaac Hayes, was part of the Church of Scientology who forced him to speak out against an episode where they make fun of Scientology. He had apparently recently suffered a stroke and the Church of Scientology swooped in while he was vulnerable and started make a bunch of big decisions without his input, including forcing him to quit South Park. He later passed away from another stroke which is largely speculated to have been caused by the CoS not allowing him to seek proper medical treatment to recover from the first one and forcing pseudo-scientific "alternative medicine" practices onto him that eventually lead to another stroke which did him in. This information was corroborated by statements his son made during an interview in 2016.

Troy McClure retiring…it still hurts remembering why he had to be removed from the series.