The issue here is that Russia has a lot of nukes. Enough nukes to end the world. If you think you know how to set up an UN that can solve the nuclear chicken problem, please go ahead and communicate your proposal.
I don't. But the UN is based on the assumption that the biggest holders of nukes are both rational and restrained. And Russia at this point is neither. And so the UN can't work. The obvious display of impotence, and Russia BS-ing everyone else in the UNSC, is in itself a huge problem for the UN system.
The UN isn't JUST a discussion-club. It is also based on a set of principles. Most important here is the inviolability of recognized borders and sovereignty. And Russia is making a mockery of all of it, and the UN can only sit there and take it. It is a not a good look. It is a real problem. If someone in the upper echelons of the UN system wanted to troll the UN, and everyone else, and make it irrelevant – then you could hardly do a better job than the Russian government right now.
Sure, most of the rest in the UNSC will restate the principles (as they do), but Russia will keep trolling them – with or without the tacit consent of China, possibly India, et al. – and that's all the UN will be able to do.
The UN system will only be able to save itself when it manages to clearly state that Russia is a direct threat to all if it – which it is – and even the Chinese, Indians etc., get on board with actively enforcing the principles the UN is based on, in direct contraventions of the Russian disruption of all of it. If they in fact want the UN system? If they don't, then letting Russia continue, in effect tacitly endorsing it, makes perfect sense.
And that doesn't mean all and sundry have to military-up and head into Russia to fight a war. What should happen however is a general condemnation of Russia, and global sanctions.
But that's not going to happen like things stand. Maybe if Russia really starts nuking other countries? Who knows...