I have just clean installed W11 Pro using a USB made by the MCT on a laptop with Modern Standby. That too had bitlocker encrypted drives by default.
Oddly, at no time was I asked to save any key, nor did Control Panel say that bitlocker was turned on. The properties for C: however showed it was encrypted, and the command Manage-bde –off had Control Panel showing 'Decrypting...' for quite some time until it was done.
Actually, this PC had an OEM W10 Pro on it when I bought it, and that too was in the same state - bitlocker encrypted drives, but Control Panel still saying 'Turn on Bitlocker'.