Do we have confirmation that it’s a must to upload the key if you use an MS account with Windows? Is it proven that it's not possible to configure Windows to have an MS account linked, maybe even to use OneDrive, while not uploading the BitLocker key?

Btw - my definition of “possible” would include anything possible in the UI - but if you have to edit the registry or do shenanigans in the filesystem to disable the upload from happening, I would admit that it’s basically mandatory.

I just checked on my personal desktop, which has Windows 11 installed using a local user account and is signed into my MS account for OneDrive and my account is listed as having no recovery codes in the cloud. I don’t recall editing anything in the registry to accomplish this it was the default behavior for having a local user account. I copied my recovery codes when I built the machine and pasted them into an E2EE iPhone note which should allow me to recover my machine if disaster strikes (also everything is backed up to Backblaze using their client side encryption).