I quote from Pjotr’s fine Easy Linux Tips project about Grub customizer.
Don’t use Grub Customizer
- There’s also a third-party tool called Grub Customizer, which massively complicates your bootloader. It heavily changes the contents of the system folder /etc/grub.d , which is where important parts of Grub reside. These changes don’t disappear, when you remove Grub Customizer after using it!
In that system folder, Grub Customizer changes files into so-called “proxified” files, which creates a complex and unclear situation. This additional thick layer of complexity may have something to do with the problems it can cause: the more you complicate something, the bigger the risk of failures…
Unfortunately, Grub Customizer is nowadays present in the official software sources (in the community controlled Universe repo, to be exact). This doesn’t mean that it’s OK to use now!
The main problem with Grub Customizer in a nutshell: as long as it works as expected, all is fine.
But when there is a problem with it, removing Grub Customizer and trying to boot without it can create big difficulties. Because the program has done major changes in /etc/grub.d, which would all have to be undone manually. For uninstalling Grub Customizer after using it, does not remove its changes.
That’s the downside of the complexity it adds. And for what? For a few things, most of which are non-essential, that can usually also be done without adding a thick layer of complexity…
Grub Customizer (grub-customizer) may look easy and nifty, but can mess up a vital part of your operating system. Your bootloader is as vital as it gets: after all, a system that won’t boot anymore, is useless.
Furthermore, most of what Grub Customizer does can also be achieved by other means, without adding thick layers of complexity “under the hood”.
If you would like to know more about this: a more detailed analysis of what Grub Customizer does, and how you can (hopefully) undo the complexity it has caused, can be found on this page (with screenshots).