linux 4.15.0-21-generic messes up plymouth and no logo on luks password prompt

[Bump]

Old problem with 4.15.0-20-generic:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1768647

New problem with 4.15.0-21-generic: installing packages as specified in mentioned bug, the kde logo does not display properly at password prompt for luks. See attachment.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1770475

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Bump (bump55)]

At least allows me to enter the password but it's not a expected behavior.

[Daniel van Vugt (vanvugt)]

Please run:

  apport-collect 1770475

on the machine. If you can't then please describe in more detail why the command isn't working.

[Launchpad Janitor (janitor)]

[Expired for kubuntu-default-settings (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for plymouth (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for kubuntu-settings (Ubuntu) because there has been no activity for 60 days.]

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]