I can confirm that after applying the update I do not get stuck any more on the splash screen with an external monitor attached and GRUB_CMDLINE_LINUX_DEFAULT="quiet splash".
Ubuntu 20.04.1 LTS plymouth: 0.9.4git20200323-0ubuntu6.2
I can confirm that after applying the update I do not get stuck any more on the splash screen with an external monitor attached and GRUB_CMDLINE_ LINUX_DEFAULT= "quiet splash".
Ubuntu 20.04.1 LTS 3-0ubuntu6. 2
plymouth: 0.9.4git2020032