I am playing a game passed the turn limit for fun as not much happened before the limit. One thing I noticed is the moment the game officially ends all the ai players will try to ally up with all other ai players even stopping wars to instantly become friends.

 Another issue is I don’t know if this is because of after the turn limit or just a problem with war support, but I declared war on the strongest empire and immediately had to surrender. When I declared war no fights happened or anything I had a war score of 110 for war support and the enemy empire had 250 war support. It wouldn’t let me end the turn until I surrendered. I had to surrender a war and give away all my stuff when not one fight was fought or even anytime passed. 

looks like a known bug, I once had an AI who declared war on me and I had to accept its surrender

but I do not understand how WS can go above 100.

WS can go above 100 because you get +10 extra war support from each grievance you have active at the moment of declaring war that are added to the war support you have at any given turn.

Ah I see. War Support can't go above 100 but War Score can.