警告：mysqli_stmt ::bind_param（）：変数の数がプリペアドステートメントのパラメーターの数と一致しません

?の周りの引用符を失います 11の代わりに10のパラメータを使用します

これの代わりに：

$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);

これを試してください：

$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);