The Ubuntu 22 installer says that it is necessary to reboot into Windows and disable BitLocker, offering a QR code and a link to https://help.ubuntu.com/bitlocker (which links here).
However this is not correct: Suspend Bitlocker before starting the Ubuntu installation and you will avoid the lengthy procedure of decrypting and re-encrypting the disk (which spoils your SSD/NVMe as well).
I also shrunk the Windows volume using diskmgmt.msc so that Ubuntu would have no issues finding the free space where to install.