I got this query while distrohopping. On Linux I have to enter my password erveytime I boot to decrypt the disk. But on windows I never had to do it. The first time windows bitlocker asked for password was when I booted into windows after installed Linux. Why is it so?
That is not the point of TPM only unlock. Tell me, can you access the files on a windows system that automatically unlocks bitlocker and then boots to the windows login screen? What can you read without a user password? If you try to boot a different OS and read the data from there, the bitlocker encrypted drive will not be automatically unlocked.
Bitlocker TPM only mode is ment to protect against a stolen hard drive and attacks in which the whole laptop is accessed by attackers (like someone breaking into your hotel room while you are at breakfast). Now bitlocker is broken in TPM only mode and many vulnerabilities exist, but conceptually its purpose is not only to protect against a stolen hard drive.