Предупреждение:mysqli_stmt::bind_param():Броят на променливите не съвпада с броя на параметрите в подготвеното изявление

Загубете кавичките около ? и използвайте 10 params вместо 11

Вместо това:

$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);

Опитайте това:

$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);