Why does Sun Tzu's "Art of War" provide less culture/tourism?

[rhetorician]

I am currently playing as Spain and accepted a trade deal from Rome which consisted of Rome offering Sun Tzu's (the great general) "Art of War" and some coin for my "Yoga Vasitha" by Valmiki." I thought the AI was being silly again and eagerly accepted the deal. But to my surprise, it turns out that the "Yoga Vasitha" provided me with 4 culture and 4 tourism, while the "Art of War" only gives 2 each. How is this possible? I thought all great works of writing provide the same yield. I've been researching this for the last 30 minutes and can't find any answers. Does anybody here know why the GG-generated work of writing gives less yields?
See screenshots below taken from the trade screen.

Yoga

• rhetorician
• May 11, 2021

Art

• rhetorician
• May 11, 2021

 

[rhetorician]

So, I investigated this some more. Turns out, it's not the Art of War that gives less culture and tourism. It's the Yoga Vasistha that for some reason provides the double yield. After I completed the deal, Rome got the increased yields, so it's not some bonus that my civilization is getting. I find this really perplexing and can't continue my game until I figure this one out

 

[MrRadar]

Your answer is here.

 

[rhetorician]

OMG, MrRadar, you have saved me from going down this rabbit hole any longer. I can now carry on with my game and enjoy OP Spain. I don't know why I always do this, but when I run into a mystery like this one, I can't continue to play until I figure it out.