Notebook keyboard is not working in X11 with current kernel

It started during the last days of lubuntu 20.04 and is still present with 20.10

The last kernel I have (know) which is still working in X11 with the keyboard is 5.3.0-55-generic
Current not working kernel is 5.4.0-54-generic

The mouse (touchpad) is working with all kernel versions.
The internal keyboard is working on grub-menu and
when connecting a external usb-keyboard to switching to tty (ctrl+alt+f2) it is also working there … but not when returning in the X-environment.

with 5.4.0-54 (not working) – I have this additional part in the xorg.0.log

[    11.722] (II) config/udev: Adding input device ELAN0501:00 04F3:300B Mouse (/dev/input/event8)
[    11.722] (**) ELAN0501:00 04F3:300B Mouse: Applying InputClass "libinput pointer catchall"
[    11.722] (II) Using input driver 'libinput' for 'ELAN0501:00 04F3:300B Mouse'
[    11.722] (**) ELAN0501:00 04F3:300B Mouse: always reports core events
[    11.722] (**) Option "Device" "/dev/input/event8"
[    11.722] (**) Option "_source" "server/udev"
[    11.725] (II) event8  - ELAN0501:00 04F3:300B Mouse: is tagged by udev as: Mouse Pointingstick
[    11.726] (II) event8  - ELAN0501:00 04F3:300B Mouse: device is a pointer
[    11.728] (II) event8  - ELAN0501:00 04F3:300B Mouse: device removed
[    11.753] (**) Option "config_info" "udev:/sys/devices/platform/80860F41:02/i2c-0/i2c-ELAN0501:00/0018:04F3:300B.0001/input/input10/event8"
[    11.754] (II) XINPUT: Adding extended input device "ELAN0501:00 04F3:300B Mouse" (type: MOUSE, id 11)
[    11.754] (**) Option "AccelerationScheme" "none"
[    11.754] (**) ELAN0501:00 04F3:300B Mouse: (accel) selected scheme none/0
[    11.754] (**) ELAN0501:00 04F3:300B Mouse: (accel) acceleration factor: 2.000
[    11.754] (**) ELAN0501:00 04F3:300B Mouse: (accel) acceleration threshold: 4
[    11.758] (II) event8  - ELAN0501:00 04F3:300B Mouse: is tagged by udev as: Mouse Pointingstick
[    11.759] (II) event8  - ELAN0501:00 04F3:300B Mouse: device is a pointer
[    11.762] (II) config/udev: Adding input device ELAN0501:00 04F3:300B Mouse (/dev/input/mouse0)
[    11.762] (II) No input driver specified, ignoring this device.
[    11.762] (II) This device may have been added with another device file.

The rest looks like just renumbering the "event"s.