Hello everybody
it doesn't work anymore, the bootspalsh with plymouth.
I installed a different theme from the default, and now at startup I only ever have the grub screen.
i tried to uninstall and reinstall but nothing.

ok. Solved.
the etc/default/grub file had mysteriously disappeared. I do not know why.
now all ok.

It happened to me also after latest update. To recover from this issue I had re-install grub-pc (apt-get reinstall grub-pc). However, since it re-install the factory version of grub file, I had re-apply all my customization in my grub file (framebuffer settings, etc..) again.