A homophobic pun would typically fall under the category of "a pun that uses two words that sound the same but have different meanings." This type of pun can be crafted to play on words related to LGBTQ+ themes in a derogatory or mocking way, which may propagate stereotypes or homophobic sentiments.
Note that while a pun may use wordplay, its context and intent are crucial in determining whether it is offensive or harmful.