I play against the Extreme AI a lot. I’ve noticed that with each patch it gets better and better at picking fights, and micro prioritising. Most notably it excels at allocating the amount of units it takes to clean up your own units (e.g it will send one spear vs a low HP knight but 2 for a full HP one). I’m pretty sure it also still ‘knows’ some information on how much army you have at any given moment.
One recent change was that it can’t be forced to run into TC fire as often (though it still happens). And now uses rams like no human player can. The downsides are that it still doesn’t know how to fully wall in early game and places camps in unsafe areas, sometimes even on human player’s res right under their noses.