Or maybe you just jumped to conclusions without even investigating why would that happen. Or even better, maybe you could post that situation as a question just to check if something was missing in your analysis. But no... i just went on accusing Pdx, accusing other posters, and now you even accuse that your lack of understanding the game is Pdx fault.
Bravo!
Actually, it is PI's fault to a degree. If you want to, through the game's interface, learn what any number of dozens of important rules are...you can't do it. It has improved in recent patches, but a distressingly large number of the game's rules wind up being learned via "trial and error gameplay"...in a strategy title!
What factors into an assault? Nope.
What's your combat width? Can't check that without going into battle or memorizing your base width to sum with tech.
Why can't you CTA your ally at war? Oh, because one of you happens to be in a war with a minor participant and OBVIOUS LOGIC states that you then couldn't have them in both wars!
Back when terrain % were a thing, what influenced those? PI told us half a year later but not in game then took it out.
What are the rules for when rebels change your religion or just have other penalties, without memorizing it/looking it up in external UI?
Which peace deals actually cost diplomatic points, and which ones don't? When can you trust the UI in this regard?
What is the formula for gaining army tradition? Naval tradition?
What kind of peace deal is required to stab hit nations, and why does it change? Which patch notes described when this mechanic was changed?
These are just a sampling, some old, many still relevant. While OP certainly jumped to conclusions about the AI in a semi-inappropriate fashion here, it's hard to fault him. We have historical examples of bugs allowing the AI to cheat inadvertently (like stacking attrition not counting, that somehow didn't apply for humans), gobs of examples where there's no ready way to know the rules of the game you're playing, and even two non-confirmation bias cases of outright wrong percentage displays that have since been patched out (claim fabrication percentage, defensive terrain %...latter removed entirely and the former made accurate as far as testing can tell).
I would suggest taking this as a valuable lesson about jumping to conclusions about the AI.
Also not blaming everyone around you when you're wrong about something. It makes you look childish.
It might be best not to go pointing fingers too much in this regard

.