Checking around my potential enemies' economic production and compared them to mine, I noticed their production appears to be lower than it should. Actually after checking all the other nation's core province around, my production at core province is higher even though all our buildings are the same level (this is the Arms Race map, all cities starts with the same building).

For example, I have a double goods producing city with max buildings (no naval base) and morale, it produces about 12k goods, while every others only produce about 7.5k goods (same buildings and morale, their city is still undamaged). Realizing this I'm starting to doubt the production value we were given of foreign nations, I'm also unsure if my own production value is even correct now.

Is this a bug or intended?

Not yet as I'm just aware of this now.
I see, I guess I'll have to experiment on that.

Visual references for what I'm talking about, compare the value of goods and money production:



Above is the core provinces of foreign countries, with the exception of East Texas with an extra naval base, all their buildings and morale are the same. No one invaded them yet.



Above is the occupied provinces by a foreign power, I can't tell if all their building levels are the same, but they're generally close enough.



Above is my core province and provinces I've occupied, for some reason mine produces more than others both in core and in occupied.

This is documented on the Japanese server, but I'm assuming this probably happens elsewhere also.

After I got granted a Share Map, I see their production value increased to the same of my levels. So It appears to be confirmed that you aren't actually seeing the production value of foreign countries you aren't sharing map with.