It's different. 9/11 was an outside foe, which was dismantled by US forces, and its leader was executed. America "won" against the perpetrators of 9/11 in the conventional sense.

You cannot defeat MAGA the same way: the "enemies" are among us, and they aren't going anywhere.

There's how the people in general remember, and then there's how the politicians and the institutions remember. If nothing else, the changes in institutions will have effects reverberating for decades, with the most obvious institution being the military in each country that expected to fight a war under a NATO umbrella with an American general in charge.

If I'm a German or French or Swedish officer, especially if I'm suddenly in Greenland, I'm going to be thinking hard about the changes to come in the next few years so that they're not all dependent upon a friendly America. If nothing else, they're all getting ready now to operate without any Americans in the loop, since it might be Americans they're fighting. That means the entire NATO command structure, which presumes American dominance of it, is now an obstacle to avoid rather than a resource to share. Every PM is asking the head of their air force if they can fly their F-35s without the Americans knowing about it and possibly shutting them down remotely.

There's a story going around today in French newspapers about how French and Ukrainian intelligence fed US intelligence some false strategic info to see if it ended up in Russian hands, which it did within days. Now Ukraine is consciously breaking its relationship with US intelligence because it can't be trusted, while getting closer to French and German intelligence. I suspect that the UK is also carefully looking at what's shared via the Five Eyes and decided what it can/needs to withhold.

9/11 - and the US response to it - is still very much remembered by people outside of US as an example of how US foreign policy works in practice.

You are talking about the US, the others do not.