AirPods Pro 2 not pairing after replacing lost earbud

Hello. Here is the situation: I lost one of my AirPods Pro 2 earbuds and bought a replacement for the missing right earbud. However, to pair them, I had to unpair the set from my iPhone. Currently, no nearby devices—neither friends' phones nor a laptop—can detect the earbuds. I tried resetting them by holding down the button on the back of the case, but that didn't work. I suspect that the replacement earbud might have been linked to someone else's iCloud account, causing the entire set (including the original earbud) to become associated with that other person's iCloud. What should I do in this situation?