The Daily Value (DV) differs between the health ministries of different countries, so France might recommend a higher or lower intake than Germany, etc. With B12 specifically, since it’s a water soluble vitamin, average requirements can fluctuate by a lot, and intake leading to toxicity is near impossible, so buying a brand containing 800% of recommended daily intake, does not hurt you.
Some people have a very low absorbance rate of B12, since it’s based off of Intrinsic Factor (IF), which is a stomach secrete, so adding more to a product just to be safe is what most companies do.
Ok !! I think I’ve got it.. As a European, I interpreted the comma on 41,667% as a decimal and not as a separator (as used in the US and UK). This means it’s 41 667% as I calculated. This seems to be the most obvious explanation to me (even though the comma isn’t present on other American brands). Bit confusing but I think it’s solved.
Another important aspect of B12 (and folate) is to get the methylated form that is better absorbed by the body. A lot of people struggle to absorb synthetic B12 supplements.
https://www.livestrong.com/article/454179-what-is-methyl-b12/
https://www.webmd.com/diet/vitamin-b12-deficiency-symptoms-causes#1
This site is pretty credible, and it gives you the whole picture.