The USSR built up infrastructure in eastern Europe. Countries like Hungary, Romania, and the Baltic States were objectively better off under the Warsaw Pact than they are today.
Lol. I am from Russia and live in one of the former Warsaw Pact countries. Are you imagining that Hungary, Baltic States, Czech(oslovakia), some of them being former members of highly developed nations like Austria-Hungary were uncivilized, industry-less, illiterate wastelands before the USSR came after WW2? The USSR did some positive things, such as building nuclear power plants (it wasn't free or out of pure altruism though, it was a part of trade deals as part of COMECON), it's nonsensical to imagine they "didn't have infrastructure" before though.
Many people in these countries still hold favorable views of Russia and the USSR
Yes. But not because the USSR and Russia are so awesome, but rather because decades later, after the fall of the Iron Curtain, people don't have much of a reason to hate either Russia or the USSR.
There are no "EU or US" propaganda campaigns against Russia. If everyone was holding "such favorable" views of the Soviet system, why did the 1989 revolutions take place? Oh, it was a "CIA intervention"... did I guess it right? Nevertheless, people are critical of the current system and the EU, but definitely not in a "it was better under the USSR" way. The membership of the West, the EU, NATO is almost unquestioned, truly almost no one wishes there was a barbed wire on the border separating the countries from "Western imperialists" anymore. Not even literal communist party members.
Their infrastructure was in most cases much better than that of the USSR, especially in Hungary, Poland and Czechoslovakia. If anything, the infrastructure was heavily lagging behind the Western developments because of the way the countries were run in the Eastern bloc. Czechoslovakia, for instance, built fewer highways under the 40 years of communism than in the post-1989 period because there just wasn't much of a reason to improve infrastructure.
Why? There weren't any competitive arrangements like in the EU now where the level of infrastructure plays a major role in whether the country is chosen as a hub for foreign investors or not. Same reason for why Polish infrastructure improved significantly after 1989.
But I am certain that without membership in the Warsaw Pact, they would have had all the industry and infrastructure anyway. Warsaw Pact was a military alliance, not an economic one, what relation does military allegiance have on the living standards or development of the country? To say that Hungary, which was drowning in debt under Janos Kadar government and Romania, one of the few communist countries where people were actually starving under Ceausescu and "commies no food lol" jokes could be a reality, is definitely inaccurate and wrong.
Especially considering that some of those countries were prohibited from joining the Marshall Plan after the war and effectively had to participate solely in the Soviet economic projects.