You may try
sudo apt install --reinstall plymouth-theme-zorin-logo
sudo update-alternatives --config default.plymouth
Select 0 for the Zorin Theme. Follow any prompts, then:
sudo update-initramfs
You may try
sudo apt install --reinstall plymouth-theme-zorin-logo
sudo update-alternatives --config default.plymouth
Select 0 for the Zorin Theme. Follow any prompts, then:
sudo update-initramfs