essentially: the parameter __proxy_cache contains a base64 encoded string with 3 other parameter names separated by semicolons

those three parameters are used as a key, nonce and ciphertext respectively (again all base64 encoded), which are passed to libsodium's sodium_crypto_stream_xor function (at least that's what it's called in php) to unscramble the actual url from the ciphertext. then it redirects there. the only purpose of obfuscating it like this is to try to make the encoded url harder to detect (e.g. by browser extensions that detect shady links :3)

all the other parameters are just filler to make it look more sus