The game speeds up in mid-turns. That is why we need quadratic bonuses to AI. CIties no longer generate yields in tens, but in hundreds. Everything is inflated.
It is not because one building or one pokicy is op. Everything stacks up. Plus base yields are much bigger - tiles produce more, buildings produce more, specialists produce more.
There’s no easy way to stop that or limit at least. Just systematic nerfing and maybe strict rules. Example. No single modifier bigger than 15%. 5 - standard building or policy, 10 - wonders, super-policy, 15 - uniques, single cases like spaceship factory.
Limit dynamic modifiers to +25. Influence, tourism, etc.