Of course there's a script; every bitcoin tx output has a script. These challenges use the standard P2PKH script, i.e.:
scriptPubKey: OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
scriptSig: <sig> <pubKey>
You know what I mean, there's no clever on-chain reward script.
Not every bitcoin tx output.
With taproot (P2TR), scripts are optional, and outputs can be based solely on Schnorr signatures.
P2TR outputs have a script that always starts with OP_1. That script may or may not commit to a tapscript.