Ask Lemmygrad

I'm not an expert on these kinds of military questions and i'm sure someone with more knowledge of how the Russian military establishment sees the situation could give a more qualified answer but here's my understanding at the moment:

It is a well known fact that both Sweden and Finland were already de facto integrated into NATO for a long time before they officially joined. Their accession was a formality that actually simplified Russian defensive planning in the Leningrad military district.

In practical terms Sweden joining is pretty meaningless as it poses no threat to Russia. And due to geography the Finish border is a much more defensible one than the Ukrainian one, plus Finland itself is kind of a nothing burger in terms of military capabilities.

Finland is a very sparsely populated country whose main population clusters are all concentrated on the southern coast, easy for Russia to reach, and it's not much of an industrial powerhouse either. Nothing compared to the military potential of Ukraine, whose army prior to 2022 had grown to massive proportions and still had huge stocks of Soviet armament, and, had it not been ruined by three decades of kleptocratic corruption, a large industrial, technological and military-industrial base inherited from the Soviet Union. Now Ukraine has been mostly demilitarized (minus the NATO drip feed that keeps them on life support) but before it was a real problem.

And though i'm sure that Russia would have preferred that both Finland and Sweden stay neutral - after all Russia had good relations with neutral Finland for many decades, and additional NATO military installations in Finland will require some reorientation and strengthening of the forces in that direction to counter NATO deployments - it's not nearly as big of a threat as a NATO Ukraine would have been.

But most importantly Finland is not and was not engaged in bombing ethnic Russians or building up an army to invade Russian territory. In short Ukraine is a vital interest to Russia, Finland is not, and Sweden just doesn't matter at all.