SpaceX Crew-11, which spent about 5 months on the ISS, got an early return trip after someone had a serious enough illness to bring them back about a month early.  The rest of the details are unknown, and NASA did cite the need for privacy, so no details have been made public in what is a first, a recall from space travel.  The photo-ops showed all of them waving, and smiling, so it doesn’t have the appearance of something tragic.  NASA even went to the extent of bringing all 4 of the astronauts to nearby hospitals, shrouding this all in a deep mystery.  This effort is good, however, and we want our adventurers to know that they are more important than spacewalks or missions. Our goals for the long run, should not have humans taking a back seat to the decisions being made, and that is commendable.  

For the 1st time in the history of the International Space Station, an astronaut experienced a health issue that required NASA to end a mission early.

Source: Why did Crew-11 return early? What NASA says about medical evacuation