It may be that it has been almost a year since Russia invaded Ukraine and Ukraine have more than proven that they can hold there own on many different battlefields so NATO are more willing to offer support in time for the Spring offensive, or it could be that something is in the wind politically in Russia.
It's always worth looking at the gas and oil situation, it's likely there is now enough gas/ oil to go around and see us through the rest of winter (the massive demand period), without too much issue. This makes it much easier to put pressure on, than say in November/ December etc, when they don't know how bad winter will be, and whether they have the supplies to last.
Now we're almost clear of that, it gives us ~9-10 months to go after him, when the only card he's got to play isn't very effective. Full spring/ summer/ autumn to come now too, and everyone will be fully geared up on oil and gas storage, so any impacts next winter are less than this winter.
It's only one piece of the puzzle mind, and it's a big puzzle.