I received info from warranty support.  Turns out that the initial "partial" encryption of the C: drive with BitLocker is a Windows 11 feature.  Again, within disk manager, the drive showed as encrypted, but not when viewing the drive via windows explorer.  So it "preliminarily" encrypts and requires the user to initiate the full encryption, where I imagine the decryption key is created and presented.  To deactivate: go to the ‘System’ tab and select the ‘Storage’ option on the right pane, scroll down to and click the ‘Advanced storage settings’ option under Storage management, click the Advanced storage settings drop-down that will reveal a list of storage options. In there, select ‘Disk & volumes’, which will open the Disk & Volumes page, where all of the disks and drives (volumes) on your computer are listed. Here, select the drive that you want to encrypt and click ‘Properties’.  Click ‘Turn on BitLocker’ under the BitLocker section, that will take you to the BitLocker Drive Encryption control panel where you can set up, manage, and turn off BitLocker.  
Just received a new XPS 9710 W11 Pro 21H2 w/ 512GB SSD from Dell.  Create a local "non-MS" account to log in and used Support Assist and the Dell Support site to download any needed drivers.  It install around 6 but got hung up on the Bios/Firmware install.  It states "can't upgrade because Bitlocker is in an encryption process". I did not manually initiate encrypting the C: drive using Bitlocker so this is happening automatically or via one of the auto installed drivers.  In control panel the C: drive padlock in unlocked with an yellow triangle and explamation point, and the option to "turn on bitlocker".  In disk manager, the C: drive show "bitlocker encrypted".   I ran manage-bde -status c: in power shell and get the following:  Size: 459.71 GBBitLocker Version: 2.0Conversion Status: Used Space Only EncryptedPercentage Encrypted: 100.0%Encryption Method: XTS-AES 128Protection Status: Protection OffLock Status: UnlockedIdentification Field: UnknownKey Protectors: None Found So what gives?  I did not want the drive encrypted.  Is the C: drive actually encrypted with BitLocker, and if so, how do I get the key?  Can I reverse this somehow, and how can I install the Bios/firmware update or rebuild the PC if needed without dealing with Bitlocker Encryption?    
Bitlocker C Drive Confused: Brand New XPS 9710 W11 Pro 21H2