)3 gpt is about right, given the minimum loan increment is 30 gold (1gpt x 30 turns). You wouldn't expect the AI to give you 120 gold (4gpt x 30 turns) for 94 just because you felt like giving it a loan, do you?
The AI will sometimes give you a loan if you request it, however. The rate is usually around 50% interest over the entire 30 turns. (But if you think of how many years are in a turn, that's actually a pretty good rate.
I think that's rather cool - the AI wanted to use you as his personal savings account!
).
Like in the previous Civs, the effects of bought tiles, social policies and units quickly snowball... The earlier you get them, the better. E.g. what if your loan allowed you to buy one extra unit for your war - without which you wouldn't have captured the AI's capital (so you'd have lost your entire army for no benefit at all)? These kinds of things are hard to quantify since each game is different. But as said, if you know you need the gold soon, then it's a good deal. Irl ofc things are different... Although maybe not if you buy 'means of production', so to speak.
