Everyone got better over Night?

No. Eight

I have played online chess since the late-1990s and I have seen the phenomenon described by the OP many times. I don’t think that it necessarily means that someone is cheating (though that is always a possibility).

A new generation of computers or a new mode of internet connectivity can increase a player’s performance at bullet or blitz chess. It may not have much impact on slower time controls. But if you play many games over many years, you will see it. You may also see this if you get a new system yourself.

i have also seen groups of players suddenly improve when a new opening course becomes available—all at once, particular variations become fashionable and old traps no longer work.

i am better at bullet but i dont think that all chess peaple got better

what I will say, when you join Rapid tournaments, there seems to be, magically, a higher frequency of opponents who (despite their moderate rating) perform with 90+ accuracy compared to normal games in the pool. maybe it's a sample size issue, idk

Right now my rating is around 1950–2050. For some reason, everyone is hesitant to say that the site is full of cheaters, and this is not paranoia, especially in the range where I am. Sometimes it’s just impossible to play.

I am having the opposite experience at the moment. My blitz rating was around 1600 and I only saw 1730 for brief periods in recent years. However, in the last two months, my ratings jumped. I started getting constantly above 1750 and now I am 1801. When I check other players profiles, I generally see a recent increase in their ratings too. Is there anyone noticed that? Is it possible that a change in the rating calculation system is made, inflating the ratings?

Wow that’s very interesting. Can one resource change power levels among such a large amount of people very effectively though?

Your Blitz Games Are Uhh

as a 1800 my situation might be different, but last week l gained almost a 100 elo while it felt easier.

but l think the main rzeason chess is getting harder is because now every techinque is know, so there no surprise effect that might give an advantage

Mostly it is variance. Many factors come into play when you are playing in the normal pairing pool. Are you getting paired against people from a different time zone, is one of you tired? Are you getting paired with tilters who have lost a few games in a row? Are you getting paired with players who play openings you find comfortable or not? The list goes on... It is just swingy with so many variables.

Regarding cheating, I almost never have any suspicious games in the normal pool, while in Tournaments there seems to be a bit more going on