It's complex and what I write here is open for argumentations.
Briefly put, insidious interactions over decades groomed certain individuals in power to promote agendas pleasing to Moscow and to stop from forwarding agendas that would have been displeasing. Who, exactly? Well, that's the thing - we don't know but can only guess - but this effect was quite visible in Finland for decades. I know this sounds a bit nutty without more context so let me try to provide it.
I am using the term "asset" in the widest possible interpretations - people acting to benefit the agenda of Moscow.
Finlandization included the necessity to get stamp of approval on all foreign policy from Moscow. The journalistic system basically recycled what USSR broadcasted on foreign events up to late 1980's.
Politicians had to get approval from the USSR embassy. How this undermines democracy should be obvious - you can have votes, but it does not matter if big brother vetoes you.
Hence you don't need to explicitly enact nefarious schemes given to you by Kremlin - you simply do not put forward agendas you guess would be displeasing to the Moscow masters. And you things you guess would please them. In this atmosphere the subtlest of hints suffice to direct policy.
Over decades, this creates a psychology of implicit submission - similar to what happens in totalitarian countries in press self-censoring and so fort. You start to guess from weak signals what the dominating party wants and impose this control. You promote those that forward your pro Moscow agenda. You chastise those too pro-western. Sometimes you promote your protege to Moscow as a steady hand and so on.
There are visible signals of this and I can enumerate few:
0)
Finland had one person as president, Urho Kekkonen for 26 years
https://en.wikipedia.org/wiki/Urho_Kekkonen
His reign was linked to very good relations with Moscow. He probably played both sides, but was in fact many ways enacting policies that were pleasing to Moscow. In the 50's this probably helped to stop explicit invasion.
1)
For example, ex. prime minister Esko Aho was in the board of Sperbank
https://en.wikipedia.org/wiki/Esko_Aho#Banks
2)
The president of Finland Tarja Halonen supported the ratification of the Ottawa treaty banning all use of landmines in Finland in 2011. This was promoted as a benevolent act by many parties. Given that Russia had invaded Geoergia 2008 this can be in retrospect considered suicidally deluded or treasonous position.
The latter one is perhaps the most egregious example of the actions of parties one would at bare minimum describe as "usefull fools". The only party that would ever benefit from Finland banning landmines is Moscow.
3)
Finland was planning a new nuclear plant starting from 2010. The tendering was won by Rosatom in circumstances that implied high favoritism toward the Russian state actor.
In 2014 after Russia invaded Crimea several municipalities pooled in extra capital to the process.
Luckily this plant project has been stopped and will never be built.
https://en.wikipedia.org/wiki/Hanhikivi_Nuclear_Power_Plant
Things like this could go on and on. But the whole point of clandestine subversion is that it's clandestine and KGB archives are probably sadly not available for academic study for decades if ever.