Jonas Quinn was a big part of Stargate SG-1 for exactly one season, so why was his stint so brief? 1994 sci-fi movie Stargate seemed primed to spawn sequels, but instead, its spinoff SG-1 became one of the most popular sci-fi shows of the late '90s and early '00s. This switch worked for the best, considering the titular gateway opened up a wealth of storytelling possibilities for a series to explore. The show couldn't afford the VFX and scope of its big-screen predecessor, but thanks to the chemistry of the main cast – Richard Dean Anderson, Amanda Tapping, Christopher Judge and Michael Shanks – it built a devoted following.
https://screenrant.com/stargate-sg1-jonas-quinn-exit-reason-what-happened/