They didn't share a border until the Soviets and NAZIs jointly invaded their neighbor Poland.

Got it bro, the actual Nazis aren't the Nazis, neither the ones who eliminated the most radical oppositors to Nazism, but actually the ones that died 26+mn of trying to fight them. God, you anti-communist revisionists are exhausting.

The Bolsheviks actively collaborated with Hitler and the Nazis, right up until Operation Barbarossa

Ugh, not this Nazi talking point again... The Soviet Union pursued for all the 30s a policy called "collective security", in which it desperately tried to achieve mutual-defense pacts with England, France and Poland because the soviets knew that their 15-year-old nation which had only just started industrializing since the end of the feudal and backwards Russian Empire, didn't have a chance alone against the Nazis with their 150 year long history of industry (as would be seen later with the USSR suffering 26+mn deaths during the war, in places like Belarus 1 in 4 people died). The USSR wanted these mutual defense agreements to the point of offering to send 1 million soldiers to France and England if they agreed to mutual defense... which France, England and Poland denied because they thought Nazis would attempt their declared goal of eliminating communisnm and massacring the "slavic untermenschen". After this was denied and it was obvious that the west would rather see the USSR invaded than reach a mutual defense agreement, they did the only possible course of action: delaying the war as much as possible to prepare for it and industrialize a bit more. That's where the Molotov-Ribbentrop pact takes place, not before a decade of exhausting every possible negotiation route with France and England in opposition to Nazism.

The fact that the USSR then proceeded to (rather bloodlessly, around 50k deaths overall, very comparable to the oppression within the USSR itself) invade Poland, has to do with the USSR not trusting the Polish government. Why? In 1917, the Bolshevik revolution drafted an unprecedentedly progressive constitution which granted the right to self-determination and lawful secession to all peoples of the former Russian Empire. That's how many countries such as Finland or Poland suddenly gained independence lawfully and peacefully in a never-before-seen act of respect of the right of self-determination. What did Poland immediately proceed to do? Become fully nationalist, ignore the right to self-determination of other peoples, and invade Ukraine (and later the USSR) in an attempt to gain territories they considered theirs by historical right. When they had conquered a good chunk of modern Ukraine and Belarus, the Polish Government decided it was a good idea to start a war against the USSR, since the USSR was plunged deep into a civil war and didn't have many resources or troops to defend itself, and some conquests and victories could grant them a positive peace agreement which granted the territories the Polish Nationalists considered theirs (while ignoring the right to self-determination that the Bolsheviks had granted them less than two years earlier). Poland was also happy to make peace and appeasement treaties with Nazi Germany as long as they could also get some territorial gains from Czechoslovak land.

Similarly, Finland in 1917 after gaining independence, was plunged into a civil war between communists and whites, which the latter won and proceeded to imprison communists in Finland who had supported the Reds, around 80k of which some 12k died (funny how nobody talks about that). The USSR had reasons to suspect of a possible alliance between the Finnish government and the Nazis, and proceeded to invade Finland. After the failure of the invasion, as you said, Finland joined the Nazis.

Blaming the USSR for entering a non-aggression treaty with the Nazis, when all western nations had done it, and after 10 years of the USSR trying to make mutual defense agreement with Poland, England and France, is at best ignorant, and at worst purposefully misinforming with an agenda. The USSR had reasons to suspect of Poland and Finland (especially given its history of constant betrayals by all European powers since the October Revolution, with 14 countries sending troops to aid the Tsarist loyalists against the Bolsheviks) and, while outright invasions may not be justified, it could all have been prevented if the western powers had actually agreed to fight nazism. It's absolutely nuts to blame the USSR and call them "collaborators with Nazis" given the historical background of the two decades before the war, especially the latter.