Does buffered magnesium glycinate actually matter?

I keep seeing "buffered" on magnesium glycinate labels, but it's not always clear what you're actually buying.

In many products, it means magnesium bisglycinate has been combined with extra magnesium oxide. That isn't necessarily bad, but not all of the elemental magnesium is coming from glycinate.

I'd check the ingredients and elemental magnesium rather than relying on the front label.

Has anyone checked this before buying?