Arah gates always opened
Check recent update notes.
Those from December 14 ?
“The gate to Arah in Cursed Shore will now only be closed when events directly in front of it are active. "
Then it’s bugged (or was bugged, don’t know, don’t stay near that gate enough).
Before, you would see the WP and Dungeon as not contested but once you got there the gate was closed (unless the chain was won of course). However during the defend event, the gate would remain open.
So it would seem that this was fixed (or that it only affected my server).