Possible reasons:
Goverment of finland gave order to house owners to build basements incase there will be war.
Russia finland money deal russia own finland money economy in finland is on the peak inflation is on the peak and ecb not give anymore more money to finland to invest in construction , russia knows this and economic problems making finland vulnerble.
Finland is not in NATO so no protection.
Usa or nato can not protect finland if you not in nato.
Also western countries and usa dont have anymore resources to send finland as all the resources and funds been sent to ukraine.
Perfect location russia will get sea and good part of land.
Even there is no war finland debt ceiling can not be lifted any higher so and if your enemy knows about this then yes.
next target will be other countries in eastern europe that have russian speaking populations,
putin will argue, if the poles, ukranians, latvians, estians, moldovians are allowed to declare independence from russians than it should also be allowed to do it vice versa, because they currently think the russians are some kind of labour source for their oligarchs.
if we look back into european history germans ididn't want to live under french oligarchs later poles didn't want to live under polish ones, now russian want autonomy.