Why is that a bad thing?
Is was common to buy Adm and maybe Dip tech 9 and 10 with 5-15% penalty and then, with 3 ideagroups unlocked, the pressure to tech up Adm and Dip is alot less and you can let the cost accumulate until you either get Colo or decide to dev for it.
For me the new system does the exact opposite. It feels like the game is telling me when and where i have to stop buying tech and wait or dev for the next institution.
Instead of the 5 and 18% which tech 9 and 10 had previously if you got unlucky and had Colo spawn right in 1500
you now have 15 and 30% every time. No exception. No variation.
To clarify I think the change as concept is a good thing. But implementation is not working. AIs completely don't understand it and they are 50 years worse because of it in 50% of games. They lost ideas, lost even tech, colonize slower, conquer slower, have more problem with money etc. It's like with estate change. They made it and even now AIs don't use them. But at least it didn't make them worse in a sense. Tech change makes them worse because they don't have ideas, and points for other things in the same timeframe as before. The PDX fault is that they didn't see this coming. Like plan of this patch wasn't to make AIs 2 times worse but it happened. Now you seriously need to play on very hard to get the same difficulty as normal before. And very hard was scrapped. There is no very hard anymore in the game because very hard is now on old normal level only.
Tech change had huge impact on all AIs across whole game. They shouldn't approach it with new studio. They overestimated and believed they can predict all this code with new studio. And they clearly can't.
And is this a game-breaking bug? No. We had much worse. I will live and play with settings that hides this botch-up. But you never know when one more bug will break the EU4 community. Like the system in which you release mechnics rework in DLC and next patch you need to completely rework it because it breaks the game, shows how bad things are. And to makes matter worse the rework in next patch can make the old DLC completely irrelevant, pissing off people at the same time that bought the previous DLCs. This will blow up eventually.