Nothing changed, really.
Politically, the most substantial thing that has happened was presidential elections held in March. One could argue that the newly acquired confidence that Putin's re-election instilled in the regime is what is driving this, but without direct evidence to support this view, of which to my mind there's none, one would be at risk of committing a post hoc fallacy -- it may sound commonsensical, but if one were to rely solely on common sense and logic, it should be equally plausible that whatever new confidence was acquired should have led to a softening instead of a tightening. Besides, the outcome of election had been all but decided long before, so not so much of a confidence boost there.
Which is why I would argue that what we see is simply the continuation of the regime's attempts to control all aspects of Russians' lives that have been going for years now. But this still leaves the question why rappers and why now unanswered.
Why now is easy -- it's in the last year or so that the Russian music scene has exploded with new performers. Many of them are rappers indeed, but they aren't the only ones. It's an interesting phenomenon in itself when a teen-aged girl who was uploading her own soppy music on social networks for fun just a year or two ago is suddenly catapulted onto the late night shows without any help whatsoever other than her internet fans ceaselessly polluting the web with links to her art.
Why rappers is more complicated. Official reason would most likely be along the lines of the state having to protect the Russian youth from obscene language rappers use or the way of life they can be said to advertise in their lyrics.
But for incidence of Russian mat to be blamed on rappers, there would need to be a shortage of other vehicles by means of which it travels across the Russian society, which there's none of. When officials as high as Lavrov who was caught a couple of years ago murmuring "debily, blya" to journalists (basically calling them idiots but in a more expletive way than the word "idiots" would convey) who were too noisy during the press-conference are known to use mat or when the military half of which is still conscript-based is known to run on mat -- if you understand Russian, watch the video from several days ago where Russian coast guard apprehends Ukrainian gun boats near Crimea, which was shot from a bridge of a Russian ship; like every second word from, apparently, a commanding officer is mat -- you can't really blame it on rappers.
As for the way of life they advertise, Russia would have to not have been singled out as one of the world's worst performers with regard to HIV by WHO, which couldn't have possibly happened in just one year since these rappers appeared on stage. Neither was Russia any more drug-free before them...
All in all, real reasons lie elsewhere and are political. Perhaps, due to their quite limited sense of taboo, it is, among all other performers, rappers in particular who you can't trust with not switching from rapping about gang bangs and shooting drugs to corruption, Putin, Stalin, Navalny, level of abuse in law enforcement and penitentiary systems, etc. Which is what happened to rapper Face. He started with "I'm having sex with 38 girls" in, I think, 2016 and graduated to the themes I've laid down this year. Given that their audience mostly is otherwise politically indifferent Gen Z, a section of society that is very young, active and has all the time in the world to, say, attend Navalny's protests is thus being exposed to what Russian authorities wouldn't want any Russian to give much thought.
Second, rap may be seen as particularly western music genre and cultural influence. For a country that likes to portray itself and to some degree think of itself as non-western, Russians are already heavily westernized -- youtube, facebook, iphone, etc. are natural part of Russians' vocabulary, minister of culture is beside himself that Russians choose to watch Hollywood films instead of Russia's in the movies, and now rap? What's next? Western-style democracy, government transparency? As Russia is finding itself in prolonged confrontation with the West, at some point you need to put a stop to this -- how are you supposed to fight your enemy, when your people are culturally aligned with it?