I am 90% sure it's looking at month long usage trends now and punishing people who utilize 80%+ week over week. It's the only way to explain how some people burn through their limit in an hour and others who still use it a lot get through their hourly limits fine.
It's hard to say. Admittedly I'm a heavy user as I intentionally cap out my 5x plan every week - I've personally found that I get more usage being on older versions of CC and being very vigilant on context management. But nobody can say for sure, we know they have A/B test capabilities from the CC leaks so it's just a matter of turning on a flag for a heavy user.
someone did the math and posted it somewhere, I forgot where, searching for it again just provides the numbers i remember seeing. at the time i remembered what it was like on pro vs 5x and it felt correct. again, it may not be representative of today.