In general, I think it's okay to make design tradeoffs like that, because higher levels of vitamins beyond what you really need aren't necessarily better. But you could certainly ask them about it.

I'm not going to get into it because this stuff gets complicated really fast [1] and two non-scientists debating it on the Internet gets silly.

[1] https://ods.od.nih.gov/factsheets/Magnesium-HealthProfession...