The main reason is that the fall of AES (Already Existing Socialism) resulted in a catastrophic rightwing backlash. All the reactionaries that were kept in check under communist rule suddenly crawled out of the woodwork, whether we're talking fascists or the clerical right wing. Soon, these two began to join forces and they were actively encouraged by Western powers to do so as the strenghtening of reactionary tendencies was seen by "moderates" in the US and EU as a safeguard against a return of socialism. This was not an organic movement. But due to the economic devastations of neoliberalism that soon swept the Eastern half of the continent, due to the power vacuum following the complete collapse of the ruling socialist parties and due to the left being widely discredited by the recent collapse, this manufactured reaction could easily take hold. Examples for this are the neonazi structures in Eastern Germany, the Orbán government in Hungary, or the resurgence of a Catholic right in Poland, all of which were movements originating in or heavily backed by the West. In Russia, the deeply reactionary Orthodox church became instrumental in constructing a nationalist ideology that could replace communist theory as a superstructure holding a ravaged, struggling society together. All of these forces could work largely unobstructed for the last 30 years, or were even actively funded by Western actors in some cases.

In regards to racism, this is made worse by the fact that many Eastern European societies just haven't seen much immigration. It's fairly well studied that racism is worse on average in ethnically homogenous areas. For Amerikans, it's hard to believe how incredibly white a country like Poland is. As AES states did not need the same amount of work migration as the West due to them not depending on a reserve army of labor to drive wages down, Easterners are on average used a lot less to the presence of black and brown people than Westerners, which makes it easier to fearmonger and demonize. It's not hard to find people in rural Eastern Germany who have never even talked to a black person in their entire life. When you expose these same people to nothing but chud propaganda about criminal immigrants, you quickly end up with people who instinctively panic when they hear that a refugee shelter is about to open up near their village.

In regards to LGBT rights, many AES states actually were ahead of the West for their time - West Germany still has worse name change and legal gender change laws for trans people than the DDR, it legalized gay sex later than the East as well. But these advances were different from what we see today in Cuba, where the government was smart enough to bring a better understanding of LGBT issues to the masses in a big education campaign that deliberately countered clerical disinfo campaigns about the LGBT community. The advances for LGBT people seen in some Eastern European countries were, most of the time, top-down decisions that lacked the backing of the grassroots movements that advanced LGBT rights in the West. An exception to this is Slovenia, which under socialism had the first LGBT film festival in the world that is still running to this day. There we could see the party and the cultural community working together and making LGBT rights a public issue. But that was an exception. So without public understanding, without a queer presence in mainstream society, it was easy to roll what progress had been made back when the reactionary backlash happened.

These existing divides deepened further in recent years, when it became evident that the crass wealth disparities between the Eastern and Western parts of Europe did not significantly lessen by joining the EU, but were actively maintained as Eastern Europe is basically treated as nothing but a source of cheap and easily exploitable labor that is viewed with constant, arrogant disdain and doesn't really get a place at the table. This disgraceful situation makes it easy for right wingers to play on the insecurities of the people and paint wokeness as a colonial project intended to further subjugate the Slavic nations.

So, in summary, this divide is unfortunately real, it is a product of material conditions, of deliberate ideological agitation and political organizing, and it would be actively misleading to equate the politics of present-day Europe with those of AES Eastern Europe. But many liberals will do just that and blame the strong presence of right wingers on horseshoe nonsense about "people not learning how valuable liberal democracy is when they still lived under communist rule." That kind of nonsense is dragged out every time a chud party wins an election there.