I tried to give another domain, for example my-evil.com, and it says wrong hash. I viewed the hash and saw this is a simple MD5 hash, so, i simply generated my own hash:

And then, send this: ?url=https://my-evil.com&h=3fec226a4d7e5c163ab93d1c5b5ed482

Flag: Ip_$po0Fing