Returning to the main topic, I do wish the tech rebalance had made any attempt to rein in war snowballing.
Killing your neighbours has always been the best strategy, but in older versions it was much easier to stay competitive by teching quickly and efficiently. Now it feels like no matter how I build my empire, my success is exclusively determined by how many AI empires I've gobbled up, which is more dependent on random empire generation than any choices I made.
If I don't want to gobble up my neighbours, I have to substantially lower the difficulty so I can compete with AI empires that do.
Related, I also don't like how tech scaling is tied to difficulty. You can disable it in galaxy settings, but that completely removes the changes to tech cost scaling by tier, so you end up in the same situation as 3.10 where the first couple tiers are really slow, then you blitz through tiers 3-5.
If I want to play on different difficulties, I need to fiddle with the Difficulty Adjusted Technology Cost setting to try keep my tech costs the same. It also doesn't work well with scaling difficulty, applying the full tech cost increase despite scaling difficulties being closer to Ensign than the difficulty they scale to.