Why is the response to a similar request empty?

Why is the response to a similar request empty?
0

Imagine:
There is an online game that sends a request to the server (client.рһр) with two constants and one random number, the server returns the result, and then the game uses it.

BUT!
If I send a similar request, but manually
Or even more difficult:
> stop the script before sending the request
> copy the request data
> send the same request, but manually

THEN RESPONSE IN BOTH CASES WILL BE EMPTY
WHY!?
Anyone help me please

You need to show us the code in order to understand. Do not show us the whole thing, only the necessary methods that are being called