I'm pretty sure that warning used to be on the UEFI download page for Biostar boards, but they've completely redesigned it, so if it was them, it isn't there anymore.

I've seen some Asus and MSI Boards getting only uefi updates marked as beta, with the next update, months later, also being marked as beta. With Asus, there have been allegation that they try to get out of warranty claims this way.

I've had less problems with Dell and Lenovo, which probably comes from them being more enterprise focused. I think the problem is that the for the average consumer, uefi updates are last on their mind when picking a board.

Apple, and, to a lesser degree, Lenovo and Dell, seem hardly comparable, since their focus isn't selling mainboards as a stand-alone component.