You’ve found the float problem.
You could try a double, which may seem counter intuitive, and doesn’t always solve the problem, but here’s what’s happening to you:
float isn’t accurate. There is a limited amount of storage, and it is typically squeezed into 32 bits. It is fashioned with a two part design, a mantissa and exponent. It is the binary version of scientific notation (like 2.4 e-1). However, the mantissa is limited to fewer than 32 bits. The exponent takes up some of those bits. In the standard IEEE format for this (which I think C# is using here), this means you have 24 bits for the precision (a base 2 version of the digits involved), and 8 bits for the exponent (expressing the power of 2 those digits should be shifted), and both are signed (so you have negative exponents for shifts toward very small values).
As a result of this encoding, the representation isn’t exactly. .24 becomes a close approximation that when converted into base 10 looks like a garbled mess.
It is, however, normal, and even internally, the number .24 may indeed be “known” to your C# code as the value JSON is showing, and not actually .24f.
Doubles have more precision, and therefore have a chance to be more accurate, but in practice all that really means is that the base 10 representations are different (maybe .24 looks exact, but .242 doesn’t). There are various formats, some considered non-standard.
This goes all the way down to the CPU, as it uses at least some standard for these representations which may be the same used by the language, and thus fundamentally there’s nothing you can actually do if you’re going to use floats.
You could, however, use other numbering systems. Fixed point values could be a choice, where an integer (possibly 64 bits) represents units such that you have a fixed number of decimal values that never “float” like this. For example, you could decide you want 4 digits of precision, so you’d consider all integers 1000 units, so that 240 is actually .24.
Other than that, this is a fundamental issue for which there are a wide range of solutions you’ll find all over the web, and can choose among many that might better suit your preference for a particular application.
Or, like many of us, just accept that’s how it works and forget about it.