Update: it seems Blizzard have now fixed the bug and the season is back on.
Season 4 (Source)
Our fix for the bug has been tested and deployed. The season has just resumed.
Have a good night!
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Burning Crusade Classic Arena Season 4 abruptly and unexpectedly ended a short while ago, and Blizzard are confirming that it’s a bug and is being looked into.
Season 4 (Source)
Looks like a bug. We’re investigating it.