It is possible to suspend Bitlocker. This works by writing the key somewhere on the disk. Then when you reenable it the key is removed again. This is necessary if you normally store the key in the TPM chip and you're going to do something that will break its trust, like updating the BIOS.

The recent update would suspend Bitlocker during the installation which is not a nice thing to do automatically.

It doesn't mean Microsoft has the keys though.