It's not a C# thing, it's a floating-point thing. Two numbers which mathematically "should" be equal, might not be due to rounding errors. (In python, 0.15 + 0.15 != 0.1 + 0.2.) So it's risky to compare them with ==, sometimes you'll get the result you expect (and sometimes you can be confident of that) but sometimes you won't. If you can't be sure, you should compare that they're the same within some threshold, but that has pitfalls as well.

(I feel a little silly saying "it's not a language thing" and then "in python", but there may (or may not) be various implementation details which other languages might use to get a different result.)