Been noticing that the pet derby queue for ranked matches either seems to bug or the people that join it are not confirming matches.
How about implementing a cooldown period of five minutes to these people who join the queue, but then don't accept the match?
Also the waiting on confirmation should never take longer than the time it gives you to confirm the match in the first place.
Please take a look to make sure this is working as intended. Also to prevent people griefing the queue a cooldown would at least remove them from rejoining the queue for a little while and allow those who actually want to race a chance to get in a match with the same type of people.