That’s kind of wild, I double-checked and it’s true.
Although I disagree with the second part, the Rust folks wouldn’t care about the in-memory representation as long as the compilation is on point.
Looking closer at the final enum, I guess it’s because there are nine possible cases for it, making the compiler pack it into 4 bits, with one number representing each? I checked and None is represented as 8, while 7 Somes containing a None is 0 and the full 8 Somes is represented by 1.