The installed plymouth packages look correct and the default.plymouth is the default configuration.
Can you check with debsums if these packages are correctly installed?
sudo apt install debsums debsums --silent plymouth plymouth-label plymouth-theme-spinner plymouth-theme-ubuntu-text
If they report failures, you ran re-install those packages (sudo apt install --reinstall $package).
The installed plymouth packages look correct and the default.plymouth is the default configuration.
Can you check with debsums if these packages are correctly installed?
sudo apt install debsums theme-spinner plymouth- theme-ubuntu- text
debsums --silent plymouth plymouth-label plymouth-
If they report failures, you ran re-install those packages (sudo apt install --reinstall $package).