Started new game on little map with 9 factions. At first 50 turns (while I've been minmaxing colony and pushing towards research) all mining resourses and relics have been claimed by AI, which is not great. But what is not so great that AI tends (better to say 'devotes itself') to spam starbases. It's just a sort of starbase crusade. On top of that they shamelessly build bases even in your area of influence.
And later they wonder, 'Your military buildup concers us'.
'Because you don't even want to sell that military starbase adjanced to my homeworld!'.
There is no option to remove starbase peacefully (it costs too much, and if you force another AI to declare a war on its owner, it is very unlikely to target that particular starbase). And at the moment I can remove it with force (starbases are sort of fortified) I can just flood the galaxy with my cruisers.
Another story is that usually their placement makes no sense, I could've fit 5 bases where they place one.