could be a few things. You could be getting hit from a deliverence engine (advent super weapon). Advent loyalist have a tech that spreads culture from their planets, and my understanding is that it doesnt work right and spreads from all planets from time to time.

The same unexplained culture spreading started happend to me as wella sfter recent update. There have not been an any deliverence engine shots (no announced construction, no shots visible) - culture just burst from every of my planets simultaneously.

I am worried, seriously.

This is definitely a bug. And it needs to be fixed.

I think its new behavior.  Does Cap ship culture repel now vary according to ship level?  I seem to recall Cap ships only having a -0.4 repel rate in the past?  Honestly, I haven't watched that closely yet, but I agree that it does feel different. [Edit, different, but not necessarily bad]

Yeah, regarding #2, Global Unity is bugged, and will spread culture from every planet (hostile or freindly, with or with out towers) in the most extreme cases.

But, Bilun, I disagree that it doesn't fit.  I think it will likely be the Advent Loyalist's signature tech!  Especially now that it doesn't require a bunch of prerequisite research.

The repel has always scaled to capitalship level.  Honestly I really think it could just feed different(well i nregards to advent anyway) in that both factions got a buff to culture(the loyalists moreso, but both are noticeable)

By the time you can have it you should already have spread culture throughout your empire.

L Not building any temples until you get Global unity is a bad idea(as the advent loyals strongest feature at the moment is their unparalleled T2 culture potential).  

Let's suppose though an advent loyal player does build no early temples and rushes straight for global unity: With the still fairly high tier of global unity combined with it's slow culture spread rate your empire will be filled in with culture FAR later then otherwise would be the case.  Moreover as I said above, going this route forfeits one of the biggest advent loyal advantages at the moment.

So then what use does advent have for more culture by around T4?  At this stage it's all about pushing back enemy culture, whether to cause allegiance loss or just claim any remaining neutral planets(by encompassing them in your culture).  In both cases a extra 2culture or so per world isn't going to push back enemy culture(A single temples overpowers it). Heck to actually push enemy culture back to their planet(if they build 1-2 culture centers to protect the planet), you're going to need something like 20-30 culture rate, compared to which an extra 2 culture rate is fairly small.

The consequently extra bit of culture rate essentially won't do anything on it's own(isn't going to push back enemy culture) and when used in conjunction with a culture bomb has a comparatively minor effect which likely won't "make the difference" between successfully overpowering the enemy culture or not.     Heck Confluence of the Unity at T2 will add something like an extra 6-9 culture rate to that same 20-30 culture rate culture bomb for drastically reduced resource costs at a lower tier.

Honestly I'm no sure I'd call this their "signature technology".  A lot of people got excited about the concept to be sure, but personally I think Acclimation of Will or Confluence of the Unity are much more defining(at least in each tech's current form).  Honestly the reason I feel it doesn't fit is chiefly that the advent loyals have much greater incentives to build temples rather then rely on the slow spread rate of Global Unity, and by the stage of the game this tech becomes available the benefit is too small to make much difference in a culture war.

Maybe it would fit better at a lower tier(so culture could actually get passively, albiet slowly spread while the advent expands), but as it stands it's simply not very useful in a culture war, the chief sort of culture upgrades still useful at the stage of the game it currently becomes available.

Well that's my perspective anyway.  I feel like at the moment their are simply much better things to spend money on at T4 then Global Unity(And it's pretty damn expensive to research, certainly costs a good deal more then a temple or 2 to fill in the your empire with culture).  That certainly trned into more of a rant then I expected...

I kind of concur on Bilun's view; I'm of half a mind to switch them: Loyalists get the cheaper temple of communions and Rebels get the Global Unity. Both should go down a tier.

As for the purpose of Global Unity, it is a culture-based defense network.

1. Hostile culture broadcasts will need quite a bit to push back the combined might of all your planets (even though vice versa is not true).
2. Even when every structure and ship is destroyed, you're still making culture, and all your surrounding planets are contributing, making it very difficult to colonize

No, you can't use it offensively (well, it's very difficult and your opponent has to be pretty dumb), but it has it's place. I'd also move it to the defense tree

I see no reason Mass Communion couldn't be better in both directions: discount on new temples and bonus on scrapping, same amount.

However, I wonder here... why wouldn't you drop a SB with the max culture tech? it's a very concentrated source of culture, and because of that, moves the lines more effectively. Plus, it has guns to defend itself.