Poland—1973 as the start of the junta going onwards
Hungary: 1989 Gorbachev-backed counterrevolution
Venezuela: Maduro and the idiocy of his sycophants
Turkey: has always been like this
Philippines: since the American overthrow of the Philippine revolutionary government in 1902
Cuba has never truly been democratic (so there was no backslide, at the contrary the communist government is an improvement over Batista dictatorship, and it's slightly getting better.
Venezuela is a farce since the early 1990s. It's the exact environment which allowed Chavez to seize power, as the leftist "Trumpian" answer sort of, and to be honest, Venezuela did pretty well in the 2000s but he governed like a moron... economically. Like a literal moron. The entire crisis could have been easily anticipated, because Venezuela had to know oil is a remnant of the past, and if 50% of GDP is oil income. Than you're in deep sh**t, regardless of who is iin power, unless you're able to deal with it. And he did not (and neither did the right before Chavez took power). I don't think he's an dictator, but I truly believe the country has been governed by idiots, although still more competent than the biggest idiot that ever took power named Jair Bolsonaro. And on top of that, the latter is a jerk.
There's some truth to what PSOL is saying about Poland and Hungary, in the sense that these weren't polities that ever really completed a transition to liberal democracy in the first place and so the democratic backsliding there is really best understood as the West no longer having the moral capital to force them to LARP as liberal democracies. He's also right that Turkey has always been like this and that the death knell for Venezuela was probably Maduro succeeding Chavez (I'd add that if Capriles had beaten Maduro in 2013 there might have been an Eisenhower-style consolidation of a somewhat-watered-down Bolivarian consensus, rather than what Venezuela actually got.) I don't know enough about the Philippines to say for sure but I suspect that it's, again, kind of always been like this on one level or another.
Capriles might've been better than Maduro, but I still doubt he would have avoided what was going to happen. The damage was long done. And he might have gotten all the blame, and perhaps there would have been a coup, you never know.
Guaido is also an idiot btw.
Turkey, Poland & Hungary always have been like this. And there are more Eastern European nations that will fall. Romania is probably next. In every Eastern European nation, except Czech Republic & Estonia, this could easily happen. The one more likely than the other. And in Romania the same will happen if the corrupt soccon Russianbacked socdems and far-right take power together.
It's just those semi-auth "half democracies" will all hate each other somewhat. Because Romania is going to hate Hungary, and Ukraine is going to hate Hungary & Romania for their Russian influence (and Moldova / Belarus are obviously no friends either). And Bulgaria & some Balkan nations is going to hate Romania. It's like Eastern Europe will be extremely divided again in the future, as if the Balkans weren't a mess already.
I have hopes for Poland but their demographics aren't ideal. It's way too religious.