Change Priority of a tracker item with "beta-blocker" label and save.
Priority changes and that is it.
Priority changes and "Beta-blocker" label is removed.
Check the webhook actions on the repo admin. AFAIR labeling items should trigger a webhook. What the tracker's doing after that, you'd be better off digging through the code than trying to get me to remember a 7 year old design.
Are the labels being saved into JIssues because i'm naughty and normally set them up in github