This is a common misconception. If you read the memorandum (it's rather short) you'll see it isn't true. We only promised to seek UN Security Council action. We went far beyond that.
https://treaties.un.org/doc/Publication/UNTS/Volume%203007/P...
And ended up voting with Russia anyway.
A treaty where the guarantor is known to give sketchy legal interpretations about why them backstabing you is actually faithful to the treaty they signed is barely more useful than a treaty where the guarantor won't honor their word.
The ripple effect is already there: many NATO country are now wondering whether the alliance is worth the paper it’s written on.
The promise to seek UN Security Council action is only in case Ukraine is attacked with nuclear weapons.
The language does seem really ambiguous though. I'm surprised it wasn't written more clearly.
It’s also a common misconception that NATO article 5th means immediate military action by rest of the alliance. It actually says that an armed attack against one shall be considered an attack against all, but crucially, the assistance provided is “what each of them deems necessary”
With the current administration I’m not convinced the US assistance that it’d “deem necessary” would amount to anything more than a call to Vladimir Putin to see how best to help him.