Advertencia:mysqli_stmt::bind_param():el número de variables no coincide con el número de parámetros en la declaración preparada

¿Perder las comillas alrededor de ? y usa 10 parámetros en lugar de 11

En lugar de esto:

$insert = "INSERT INTO record_user (ip,country,address,stack,skills,employment_type,city_selection,landing_time,submission_time,time_spent) 
VALUES ('?','?','?','?','?','?','?','?','?','?')";
$insert = $con->prepare($insert);
$insert->bind_param("ssssssssss", $user_ip, $country, $location, $stack, $skills, $employment, $city, $landing_time, $submission_time, $time_spent);

Prueba esto:

$insert = "INSERT INTO record_user (ip,country,address,stack,skills,employment_type,city_selection,landing_time,submission_time,time_spent)
VALUES (?,?,?,?,?,?,?,?,?,?)";
$insert = $con->prepare($insert);
$insert->bind_param("ssssssssss", $user_ip, $country, $location, $stack, $skills, $employment, $city, $landing_time, $submission_time, $time_spent);