I'm also using Firefox, so I'm not sure

but as Riamus mentioned if you're already in the A21 section it will automatically apply that filter in the search bar
I believe they use Jira for internal bug tracking, which if you are using the cloud version, after a certain number of users, they have to pay licensing per user. I had another game that I played that tried making Jira available to the public for tracking purposes but to cut costs due to Jira's licensing model they would automatically disable accounts if you don't log in after 30 days and you'd have to contact someone to get access back

(they ended up switching to another platform for bugs in the end).
There could be other reasons though, I'm just guessing here