
Go to check out this guy's twitter and this video is the first post I see:
He definitely has an endearing sense of humor lmao.
Iirc Finland gave some land to the USSR after the Moscow Armistice and they still claim it as rightful Finnish clay that must be returned, i'm not sure if they stopped doing that to get into NATO or if they are still claiming that despite being in NATO
In my experience, claiming the lands ceded in the armistice to the USSR are still rightful Finnish clay that must be returned has always been a largely fringe political position in Finland. If someone brings it up, they are almost always talking about Karjala, and there are many good reasons for that. Before the war, it contained major cities like Viipuri, a substantial part of Finland's industry and economy at the time, and was the heart of the "Finnishness" being formulated in the Karelianism of Finnish national romantics of the period and the Academic Karelian Society. Finland was being born, and its doula patriots saw Karjala as the heartland. Which made its loss very condemning for Finland and its return the dream of many patriots since then.
However, there are many good reasons why Finland hasn't pushed for it or taken it back since then. In the decades immediately after the war, Finland's survival was top priority and careful as is, so any bounce-back reconquista was out of the question. Then, as time progressed, having it back became a liability as (i) the Finnish state would have to foot the bill of Soviet decay and (ii) Finnish evacuation and Soviet Russification combined to make the lands no longer practically Finnish, meaning to bring them back would mean mass deportation (unacceptable to Russia) or a significant non-Finnish demographic in Finland (unacceptable to Finland). This is why Finland refused an offer from Yeltsin during the 90s.
Growing up, the sense of these lands were either: They're Finnish, just 'on the Russian side'. -or- They're Russian now so just move on. Nobody really pushes for their return outside of the internet and some ardent nationalist groups. What you rather see, at least, before NATO, was cooperation between the Finnish and Russian governments over these lands and their cities, cultural exchanges between the Finnish government and Karelian and St. Petersburg Oblasts, and Finns visiting and vacationing there for the history and the countryside that has that southern spirit that Finns find soul soothing:

Of course, my testimony is coming from a pre-NATO Finland. With NATO alignment, the current sentiments might easily change. It just depends on how things play out.
MFW:

Also, fun fact, Mongolian throat singing works surprisingly well in Finnish.