The EU added A+, A++ (and even A+++ for some items) energy efficiency categories for various products as more efficient technologies emerged that outperformed the original A rating. They're now attempting to reclassify the system, falling back to a simpler A to G rating. It's going to cause lots of confusion though, because a bulb previously categorized as A++, is now categorized as C under the new system.
Simpler EU energy labels for lighting products applicable from 1 September 2021 - official EU website
Wikipedia entry covering labels for fridges, televisions, etc. (but not up to date on light bulbs)