I don’t think it’s just a matter of reacting to NATO expansion like those guys would have you think. Russia had already prevented Ukraine from joining NATO with the Crimea invasion (plus earlier Georgia) and successfully muddied the waters such that almost no one in the West even really cared that much. Trump’s antics were deteriorating relations such that Macron was publically calling NATO brain-dead. Nordstream 2 was soon to come online and bring new fissures between particularly Germany on one side and Poland and Ukraine on the other, since more bypass capability allowed Russia to pressure Ukraine and Poland with gas games without giving up on German cash. They were basically already winning as they were with NATO looking irrelevant more and more by the day, they were making tons of money with western Europe which was fed up with what they saw as petty eastern European disputes threatening stable gas supply, etc.

Invading Ukraine more seriously than they had been blew all that nice position up and put new urgency and energy into the alliance, scared Sweden and Finland into throwing their lot in with NATO, moved NATO borders much closer to Russia and made re-arming a far FAR more salient issue in EU countries while also getting a jillion sanctions slapped on Russia. And it’s not like those measures would have been unexpected unlike Ukraine actually being able to fight back surprisingly well. It’s a weird anti-NATO maneuver that’s practically designed in a lab to make NATO more relevant than it had been in decades.