Why does the method "continue" running after return?

Question

.NET

Hello!
I have a .net core project with an action protected by reCaptcha.

public async Task<IActionResult> SignUp(UserSignUpModel model)
{
            var recaptchaRes = await _reCaptchaService.Validate(Request, !Startup.IsDevelopment);

            if (!recaptchaRes.success)
            {
                return BadRequest("ReCaptcha is invalid");
            }

            _userService.Signup(model);
}

For reCaptcha I use reCAPTCHA.AspNetCore ( https://github.com/TimothyMeadows/reCAPTCHA.AspNetCore)
I submit the form via axios.
The bottom line is, everything works fine on the local host, but the following happens in Azure: A
request is sent, 400 ("ReCaptcha is invalid") comes in and the user registers. I looked in chrome, only one request is sent. Maybe someone had a similar problem? Maybe .net core somehow repeats some requests in case of failure ... Maybe something else ...
Thanks everyone

Answer 1

But who knows what is written in the library that you use. Why is this needed? In my projects where I use reCaptcha, I simply send requests through the built-in HttpClient according to the reCaptcha documentation and there are no problems.