A counterpart to the question Why doesn't the Falcon-9 first stage use three legs to land?
This excellent answer states that the first stage of the Falcon-9 uses four legs because four legs are less likely to tip over. However Starhopper which is a prototype for Starship has three legs, as seen in this 150 m Starhopper test. Furthermore, four legs mean that its apothem is larger meaning it will be more stable than three legs. In order for three legs to have the same stability has 4 legs, the legs have to 1.4 x the distance from the center, so Starship might be lighter and cheaper with four legs as it can have smaller and lighter landing legs.
The answer to the question Why did the Apollo Lunar Module have four landing legs? states that
Three legs offers less safety margin for steep slopes and sideways landings.
Unlike the first stage of the Falcon-9, Starship is not guaranteed to land on a perfectly flat surface on Mars. It's entirely possible that Starship can land on an uneven surface, thus needing more stability and the need for four landing legs.
Question: So why does Starship have three legs when it's going to land on Mars? Is it simply weight, or another reason?