tl;dr: if you ever lose access to the Microsoft account you use to sign in to Windows 11 24H2, you have no way to recover any of your locally-stored data.
When installing windows and configure bitlocker you do get presented with the option to create an offline backup of said key eg to a USB drive. The same dialog also give you an option to back it up to OneDrive in addition to an offline backup.
This is a non-story
I literally bought another SSD a couple weeks ago to start the "never boot to Windows unless I really need to" process.
The dialog has for this has always offered the option to back it up to a USB drive and the dialogs function is largely unchanged the past 18 years providing access to backup up the decryption key to a local target or online.
*Back then OneDrive was called Windows Live Folders