Hole in Flag
The "Hole In Flag" revolutions - or the "Revolutions of 1989" or the "Autumn of Nations", or most commonly the "Fall of Communism" - were a wave of revolutions that swept Europe in 1989-91 and signalled the end of the Cold War. The Trope Maker is arguably Hungary, cutting the communist emblem out of the centre of their flags during the 1956 revolution.
For a fuller discussion of what led to the sudden and completely unexpected fall of Soviet Communism, you are directed to the page on the History of the Cold War.
Suffice to say, President Gorbachev attempted to reform the USSR, promising Glasnost (openness) and Perestroika (reconstruction), but was unprepared for the tide of emotion he unleashed in the Soviets' satellite states and the USSR itself. Poles, Czechoslovakians, Hungarians and many more all thought that Gorbachev would tell their own repressive leaders to extend the same policies. "Gorby save us" was the common cry.
One by one, beginning in Poland, the Communist governments were presented with peaceful demonstrations of their citizens on an unprecedented scale and for once decided to grant their demands instead of crushing them with tanks. Elections were held (except in Romania where there was a coup instead) and the Communists were universally kicked out of power (except in Bulgaria, where they changed their name into "socialists", won the first election and remained in power for a few more years).
The USSR held on for two more years before finally imploding in 1991 as its constituent republics (including Russia itself) all declared independence, leaving Gorbachev president of exactly squat. Yugoslavia also held on until 1991, when social and ethnic tensions exploded into The Yugoslav Wars - any pretense of communism was quickly forgotten and aggressive nationalism became the order of the day.
One feature of the demonstrations that became a potent symbol of the revolutions of 1989 was the flag with a ragged hole where the communist emblem had been. In Hungary, Romania, Bulgaria, Albania and East Germany, pre-war national flags had been adorned with red stars or the communist state coat of arms, and these were torn or cut from the flags by demonstrators. (The page image is the Romanian flag)
Of course, all this dramatically changed fiction. No longer living in a world where the main bad guy was red, held big parades and was easily identifiable, writers had to adapt to a new situation fairly quickly.