Apple Watch Series 10 - Harp chimes for 15 mins after turning off alarm

This has only recently started happening. I have an alarm set for 7am every morning. I charge the watch at night. When the alarm goes off, I dismiss it. Then a harp chime sounds for 15 mins (to the second). I can't find where to turn it off or how it got turned on. I wondered if it was because it was in charging mode and wanted to finish charging but putting it back on the charger doesn't stop it. I believe it has done it even when I'm not charging but I will need to test that to make sure. Any help is appreciated. Watch OS ver11.6.1 (22U90)