Grub Customizer has logic issue that could cause problems. In my case, after editing the text of Ubuntu entry in boot menu, manually add Kernel parameters by editing '/etc/default/grub' will no longer work, even after removed grub-customizer. I have to continue using the tool for the configurations.

Simon Chopin has explained in this bug report:

However, there are some customizations that are apparently not doable
by simply editing the existing configuration scripts. For those, the
program moves all existing conf scripts out of the way, and instead
installs "proxy scripts" written in a custom language that basically
filter the output of the original scripts. The language interpreter is
a standard ELF binary with standard dynamic linking, which seems to
need the whole Qt stack for some reason. Said interpreter is copied to
/etc/grub.d/bin/grubcfg_proxy, presumably so that the system keeps
working even if the user uninstalls grub-customizer.

That logic is actually broken, since removing the grub-customizer
package might lead to the removal of its dependencies, e.g. the Qt
stack, leading to a broken binary.

So grub-customizer is completely removed from Ubuntu 22.04 repository. via: ubuntuhandbook

As @krumpelstiltskin answered, the software developer has updated the app and claimed that the bug mentioned above has been fixed. It's now available in PPA.