I might have mis-configured something now my PKGBUILD use this vim like editor? I don't even have vim installed, it only print out plain text in the terminal before, how can I revert it back?
Looks like less to me. How did you open the file? Double click from file explorer? Then you need to check your default applications.
It's less after I removed it, it revert itself back to normal
As others have said, less is super useful, you should keep it installed. There are better ways to open text files with your preferred editor than removing all alternatives.
Put EDITOR=youreditor in your env and keep less. Less is fine and it's usually default for man pages too.
I could be mistaken, but that editor looks like nano, which is just a super simple text editor. Ctrl-x should bring quit the editor and ask if you want to save.
How were you editing PKGBUILD files before? A GUI based editor?
How did you open this? Maybe something overrode your default text editor application (look in settings for Default Applications).
Also maybe check your EDITOR env variable (echo $EDITOR), though that is only used when a different CLI program wants to open an editor for you (in CLI)
Another commenter said less and it's actually less doing this, it come with man package and set itself as default editor for PKGBUILD