Obviously, letting Israel get away with bombing Gaza and other Palestinian areas is part of that trend.

My point is that it’s not a “trend;” Israel has been committing atrocities against Palestinians since before day 1 and it didn’t affect their international recognition one iota. Then they committed more atrocities and were rewarded with international trade, investment and arms. Even after they recognized the State of Palestine they kept encroaching on its territory. There is no time in history when Israel didn’t get away with bombing Palestinians, and this trend holds elsewhere. International law has never applied to great powers in any meaningful sense; it’s always been a cudgel for beating smaller powers when they get out of line.

This was a strong era of international law and legal regimes were added and became increasingly more binding, not the other way around. When the USSR collapsed and Germany was unified 1989-1991 many started to envision an ‘end of history’ as the world would converge into a global liberal order etc.

Clearly the US and its allies never felt the need to follow these legal regimes, if their behavior during and after the Cold War was any indication. See: https://en.wikipedia.org/wiki/United_States_involvement_in_regime_change#1945–1991:_Cold_War. This optimism you’re talking about was nothing more than naivety that never reflected the real world, is my point. When did international law ever restrict American imperialism? Soviet? French? British? The only real difference now is that Westerners can’t ignore this stuff any more; as someone from the third world I can tell you nobody I never felt like I or anyone else were protected by international law. Iraq alone is conclusive proof that the rules based order was a farce. What you’re describing is the West losing faith in the farce they created; nobody else had any faith in this shit in the first place.

I’m not sure when exactly, probably 2010ish.

If there was ever such a thing (there wasn’t), there’s no way it can be argued to have survived the War on Terror, so it has to be before 2001.