This going to be a long list that is based on hardest difficulty and above.
1- If Malians and Mongols are on the same team,Malians suppress Mongol AI.Mongols get stuck on their base for rest of the game producing a couple of villagers and a few mangudai.
2 - If Malians played on Ridiculous and above ,they suppress all other teammate AIs production of units and go hyper aggressive producing army at a rate of multiple players total.
3- Abbasid AI is barely playable on Hardest and only playable with 1vs1 on difficulties that are above. On team games with Hardest difficulty their first attack usually coming at 20th minute mark with only 5-8 man when the game is already at castle age with large units fighting.
4- Abbasid AI is unplayable on team games above hardest.If Abbasid teamed with aggressive AIs, aggressive ones stop being aggressive barely produce units.If mixed with passive and aggressive civs,passive ones become aggresive. Abbasid only expands their base and production but won’t convert those resource into army no matter what.Being over passive makes Abbasid useless which wasn’t case in previous iterations.
5 - Only China can consistently bring down keeps with accuracy using bombards and trebuches.Also effectively use nest of bees against mass infrantry while other civs use trebs as anti infantry.Another instance maybe the efficent use of trebs by Mongols from distance against keeps.The problematic siege behaviour is still there from day 1 (Sending siege equipment very close to the keeps either not shooting or standing still etc.)
6- When faced with players massive army,all AI’s except China waste precious resources producing way too much springalds/culverins pre emptively while player doesn’t even have any siege equipment or just a little.And those springalds used for all purposes except being anti siege.
7- Delhi AI compared with last iterations, produce way too less siege equipment and massively produce war elephants instead and sends them to meat grinders.Also when Sacred site timer starts,they won’t produce army or even attempt to take it back.
8- Not all civs respond well to the additional difficulties.While China ,HRE and few others respond well to the resource bonus many are so so or not affected at all like Abbasid and Delhi.
My conclusion including why the first 4 articles happen is the base aggression and army production rate on difficulties above Hardest stays the same as Hardest and only aggressive AI’s benefit from them maybe even benefit too much distruping other civs while passive civs completely break or perform worse.Without optimizing aggression and military production in accordance with resource bonus/difficulty,anomalies like these happen.In February patch you optimized military and eco production in parallel with resource bonus and it worked.Why didn’t you do the same for the new implemented difficulties ?. I’m not being challenged more than the Hardest difficulty and i’m being challenged even less in contrast to Hardest.
I have many more observations but i have to see more of them to reach a conclusion.These are the ones which IMO impact the game most.