I'm still playing heavily modded Civ 6 with Late Game AI, Take Your Time & AI strategy tweaks.
Essentially it makes research slower by a factor of 4-7x, strips the AI of some of their BS Turn 1 perks like 3 starting settlers & 5 warriors, but gives them crazy production perks that scale up with each era.
Since research is so slow, the AI is often forced to churn out nothing but military units because there isn't anything else to build. On water maps, this sometimes results in every tile of their empire being covered in military units to the point where new builds start getting teleported to random islands.
The old AI problems still exist though with lack of aggressiveness. Sometimes I'll find one of their cities or capitals being beaten up by barb ships, then sneak attack & steal it with one of my own. Then fret that the AI is going to recapture it next turn because the city is then at low health under my command but surrounded by land units.
But the AI never attacks to retake it or even fights my own land units I buy from the city, I've been able to clear out entire islands of AI units one by one as they just stand there like bumps on a log or retreat.
I'm sure the sheer volume of units messes up some of the AI behavior, but it's annoying that the Civ 6 AI still isn't a military threat when given overwhelming numbers & odds.