that is because of https://github.com/gnembon/fabric-carpet/blob/master/src/main/java/carpet/script/value/NumericValue.java#L197

the method equals of numbers returns !(a-b> epsilon)
if any of a or b is NaN, it is true.

there for,
x == x
x == 3
x == 4
3 == x == 4
are all true🙃😄😅