I would like to be more objective to the invasion, by giving it a larger context, instead of the context of the immediate present that is in vogue. WWII resulted in over 20,000,000 Russians killed. That country suffered the worse in WWII in terms of causalities, even more than Germany and Japan who started the war. After Hitler was defeated, the Russian people, were under the lingering stresses of battle fatigue, and decided to create a buffer zone around itself, to avoid future invasion. This became the USSR. This buffer zone split Europe and began the Cold War.
When the Berlin Wall fell and then the Soviet Union broke up, Russia was once again feeling vulnerable. NATO, which had formed as a counter to the USSR, did not become dissolved with the USSR. It remained and even grew as Eastern European countries, like Poland, became part of NATO.
I can see this imbalance of Cold War power and counter power causing insecurity, since the enemy of the old USSR was growing, as the USSR was being dissolved. With Rumors of Ukraine wanting entry into NATO, this meant NATO would finally be on the border of Russia. Invasion into Russia would be one bad NATO decision away, in the minds of the paranoid power structure of Russia. Putin needed to restore a buffer on the Eastern front, since the images of another 20,000,000 citizens lost could never occur again ay any cost.
I see NATO as basically a force for good. However, with NATO being led by the money of the USA, and with the USA on the verge of its own internal civil war of sorts; social and cultural, the leader nation of NATO had become a wild card. It was not the same way USA, as when the USSR dissolved. It now had too many con artists leaders, willingly lying to the camera, to support the collusion scam.
The contemporary Democrats, say they hate the Constitution, and would like to rewrite it to form a socialist country they could set up and always control. The Republicans still wish to a have a more open and free capitalist society. Russia can no longer depend on the good old USA, where the two political parties could find ways to compromise, without spying in each other, scams, lies and cheats, like the collusion delusion. If I was in Putin's shoes, I would be concerned, since propaganda and misinformation without consequences, like in the current USA, is what the shady countries do.
Putin did not invade anything under Trump, like he did under Obama; Crimea and under Biden; Ukraine. The question is, why did Putin wait for the Democrats to be in power before expanding? Trump was more old fashion. Make America Great Again, implies Trump saw the past, as a better time. This was when things were more stable and more wholesome to where the USSR could lower its guard. Maybe Putin had hope since this vision was of the America that was trusted enough for the USSR to dissolve.
Obama and Biden both appear to hate America, they blame its all the woes of the worlds. They wanted to change it into something overly centralized, unproven and debt ridden; change of the sake of change. This vision may have made Putin paranoid, so the decided he needed to buffer up, before it was too late.