I am having this issue ...
... DOW from neighbor on or around turn 35.
... Excessive AI production (10x player) and/or gold/turn (20x player).

Followed by ...
265048
Conquest LOSS.
... another AI fell a turn or two before this picture
... it is unknown if conqueror was same civilization

NOTE:
I turned off city states, ancient ruins, and barbarians to see if it was related to those mechanics.
1) This is NOT happening every game (25..35 percent).
... The attached picture was from the second game generated with those restrictions.
2) This feels different from the usual AI bonuses.

Suggestions for countering this situation are welcome.

[game details]
Deity
Pangaea
Standard size
Standard speed
9x AI, 1x player

Seems like it might be because you settled way too close to the AI, and it is Deity after all. But the AI reacts especially harshly to proximity, otherwise it may just target city states or whatever. Did you move your starting settler? Otherwise just bad luck his city is less than 10 tiles away to the southwest.

Also, you could probably have fought this off/built military of your own, clearly you went for an extremely early second city and didn't build much of your own military (could have had 5-6 units at that point if you needed them, and recognizing you started next to a possible warmonger)

I suggest that you maybe step away from Diety for the time being, and the problem will fix itself most likely. :p

LOL -
... This post is regarding atypical production, gold/turn of AI.
... Yes, the AI can be defeated in combat quite easily (even on deity).
... I did not build next to AI, it built next to me (common).
... ... (on these settings, capitals average 10 tile separation)
... The visible build order is part of a series of 50 turn games to test/compare different starts.
... ... (this build explores early settler in relation to score [10pts/city])
... I turned off previously mentioned features to isolate cause of this atypical behavior.
... Regardless the build order, this atypical production, gold/turn is a recurring observation.

Specifically looking for tips to counter and/or information on game mechanic involved.

40 turns and 9 units visable, thats 8/40 (1 garrison) = 1 unit per 5 turns.

I guess the AI is building scouts and upgrading them to archers, clever AI. Does it still happen alot when city states are off? It could mean major starting unit bonuses for Deity AIs, certainly on immortal i've seen 4 jag warriors running around after 10 odd turns.

Build more warriors, they pwn archers something stupid.

40 turns and 9 units visable, thats 8/40 (1 garrison) = 1 unit per 5 turns.

I guess the AI is building scouts and upgrading them to archers, clever AI. Does it still happen alot when city states are off? It could mean major starting unit bonuses for Deity AIs, certainly on immortal i've seen 4 jag warriors running around after 10 odd turns.

Build more warriors, they pwn archers something stupid.

You can't upgrade scouts to archers. (Only huts can do that.)

Re: city states
AI did slow down with removal of city states (it knows how to use 'em).
Atypical behavior did not change frequency of occurrence.
Atypical gold/turn AIs with only 1 city in mid to late 20s.
Atypical production AIs with only 1 city in late 20s to early 30s.
My thoughts lean toward early GA w/atypical terrain.
Early conquest might explain some of it, but doesn't seem strong enough.

Isn't it standard for AI to get ridiculous bonuses on Diety level, to makeup for crappy AI in general?

Did you scout their terrain? Maybe they had a lot of gold and production resources. Especially if the had gold or silver, as mining comes much quicker than plantations.

FWIW, the important AI bonuses on diety, from the XML files (I think, although I could be misinterpreting some values):

Starting settlers: 2
Starting defensive units: 2
Starting workers: 2
Starting exploration units: 1
Worker speed: 200%
Unhappiness: 60%
City Growth: 167%
Production: 200%
Unit Supply: 150%
Upgrade costs: 50%

Free techs:
Mining
Animal husbandry
The wheel
Pottery

Whoa,
... 2x starting workers @200%.
... hefty bonus
That could be the missing factor.
Coupled with
... mining resource
... hills
... food resources
... early conquest of another capital (not always observed)
... could account for observed atypical production

I'm not sure that would explain atypical gold/turn.

[edit]
Question:
... what is happening to that second settler?
... when scouting, I do not always observe two cities.
[end_edit]

Well, you know, if this isn't what's supposed to happen when you play on Diety, then it must just be something that slipped through QA. Can't expect it to be perfect on release.

I can see one possibility:
- Chopping trees gives 20 shield.
- 2 free workers double speed.
- double production

If double production applies to chop-chop 20 shields thats a warrior/archer in 2-3 turns ?

Maybe in 25/35% of these games, nearby AI has resources in forest tiles, goes to chop them down for camps and accidentally gets like 10 units.

Status report.
Prognosis.
Appendectomy necessitated.