Pretty much every game I'm observing has one either 50 yr long or neverending battle/siege. The AI will never look for alternatives if a siege or battle hasn't ended in like 10 years, so it can sometimes completely bring games to a standstill (also can be kinda dumb when an armada just stays sieging somewhere while their homeworld is invaded.)
Also every game I've simmed has had the skylaxians or evuck as the primary power(s). Probably just a natural thing since they are both the most technologically proficient, but it'd be interesting to atleast have some variation or competition in that area as otherwise they are basically tech-discovery monopolies for the entire game.
Another weird thing I'm noticing is that even if the timer for the gas giant ignition runs out, the majority of the time nothing happens.
Completely unrelated, the wiki states these relationship markers exist. They don't: Unyieldingly Hated: -100 to -90 influence Abject Loathing: -100 to -90 attitude
EDIT: I know I'm probably just babbling to thin air here but I think I've got a perfect example of this standstill in action in the attached savefile. The stylaxians probably have like 500b people, god mote, and time travel, and yet can't pierce the defenses of this infinitely respawning 2-3 armadas that are there.