Please install a few old kernels manually, mark them autoremovable and run u-u in verbose and debug mode.
If u-u removes those kernels this is not an u-u bug.
Then install those again and try removing them with apt.
If apt removes those kernels than this is not an APT bug.
Please install a few old kernels manually, mark them autoremovable and run u-u in verbose and debug mode.
If u-u removes those kernels this is not an u-u bug.
Then install those again and try removing them with apt.
If apt removes those kernels than this is not an APT bug.