The old ratings were designed for incandescents, so all the modern LED bulbs were getting absurd ratings like A+++, so they just changed the scale to make it harder to get the A rating. Basically C is the new A++. So you can't compare the old scale and the new scale.
Of course, this means the previous labels on your fixtures that said "do not use bulb below class C" no longer mean anything. But these labels were meant to prevent you from using incandescent bulbs in fixtures made of plastic that wouldn't tolerate the heat, and there are no more incandescent bulbs, so who cares.
The useful thing about this regulation is they made it mandatory to specify the light output in lumens. So you can look at how many lumens it outputs, look at the power, divide, and you get the efficacy in lumen/W.
Now you may ask, why is the efficacy in lumen/Watt not what is printed on the box instead of useless "ABC" ratings? Well, it's brought to you by the same bureaucrats that give my gas-guzzling V6 a better pollution rating than my high mpg diesel, lol.
Note luminous efficacy of LED lightbulbs is not relevant unless you have a very large number of them. If you upgrade a bulb from a 13lm/W 60W incandescent to a 100lm/W 8W LED, both output about 800 lumen, and you save 52 Watts, and it does add up. But if you upgrade that 100lm/W 8W LED to a 200lm/W 4W one, you only save 4 watts.
IMO it's better to focus on quality: no flicker first, then higher color rendering bulbs which have a bit lower efficacy, but they are absolutely worth the extra watt. If you like the color rendition of halogens, the 3000K CRI90 spots from Osram are a nice match.