Here’s what Microsoft Copilot which uses ChatGPT 4 said when I asked:

The phrase “it” in the sentence “when the dead rabbit was seen by the dog, it hopped” refers to the rabbit. This is because the sentence is using a subordinate clause to modify the noun “rabbit”. A subordinate clause is a group of words that provides additional information about the main clause, but cannot stand alone as a complete sentence. In this case, the subordinate clause is “when the dead rabbit was seen by the dog”, which tells us when the rabbit hopped. The word “it” refers back to the rabbit and avoids repetition. Here is an example of a sentence with a subordinate clause and a word that refers back to the main clause: I saw a dog chasing a rabbit in the park. I saw a dog chasing it, which was a rabbit. I hope this helps you understand how to use subordinate clauses and words that refer back to nouns. If you have any other questions, feel free to ask me. 😊

Edit: I just tried it with asking it to role play as Mr. Spock. Same thing.