I don't know about Apple but Microsoft has a pretty nasty way of handling user's Bitlocker keys.

If you use a Microsoft account, your key is automatically backed-up in Microsoft's cloud. Red flag #1.

Also, as the recent Bitlocker bypass "bug" showed us, Microsoft has some way of bypassing Bitlocker encryption when it performs updates on the system. I don't know if they have some kind of key escrow or what, but either way - red flag #2.

Of course, I'd say the bigger problem is that Microsoft doesn't even give the majority of Windows users the option to encrypt their computers, by restricting Bitlocker to expensive computers and Windows licenses, while every other operating system does. So the advice to "just use the built-in FDE" doesn't work for the majority of Windows users.