It's the advent loyalist "Global Unity" technology. It's making advent culture automatically spread from all worlds rather then just the advent player's worlds.
Sad thing is that when this bug gets fixed it will go back to being useless. Even with he recent tier reduction it still comes out too late in the game for an extra 1-2.5 culture spread per planet to really make much of a difference.
If you build temples before hand you won't notice a difference as you will have already filled in your empire with friendly culture(and an extra 2.5 culture rate won't do much to push back enemy culture).
If you avoid building early temples and just rush to T5 for Global Unity you give up one of the advent loyal's biggest advantages(their overwhelming early culture advantage).
Of course the bug needs to be fixed, but I think Global Unity is is need of some re-envisioning, in it's current form it simply doesn't fit into the advent loyal's kit properly.
