As a guy who (used to) dual boot, I think I can offer some insight.

When I had Windows 10 dual booted with Linux, Windows had this extremely annoying habit of changing my UEFI boot order when it updated so that Windows was the first to boot, rather than Linux (where I can use GRUB to load Windows). I then had to manually revert the change at the bootloader.

With this exposed, it would not surprise me if their "default" implementation is to make sure Windows boots first, and revert the UEFI boot up that upon every boot up. An average user will likely not be aware of that, or the heavy Linux user who only boots into Windows occasionally.

sure, bitlocker is a major pain on my dual boot device.

But isn't that IMPROVED by open sourcing the implementation? It exposes that kind of stupid behavior, and for the implementation to be useful, that stuff can't be in there anyway. Maybe I'm completely misunderstanding what's being open sourced?

I'm not certain what is open sourced. What I saw is that Windows iis going to be able to access certain features of uefi, so they would be more standardized than anything.

Also, I didn't even have bitlocker turned on, that was just Windows being a PITA with regards to daul booting