The filibuster was a sacred cow for the Democrats too, was it not? Like when Trump was in office? There was plenty of vitriolic grandstanding by democratic leaders then just as there are among Repubs today. I do not believe the GOP ever came close to ending the filibuster when they had the chance, as did the Democrats recently by only 2 votes.
A carve-out is basically an exception to the filibuster rule, otherwise known as the nuclear option. And we have Harry Reid to thank for that, do we not? I haven't researched it, don't know it was ever used before that but I doubt it. Have the Repubs used it for anything other than judges, justices, and executive branch appointments? Not that I know of, but here we have the democrats trying to use the nuclear option for something new, and let's not obscure what that means: anything that the majority party wants to pass and doesn't have the 60 votes in the Senate can be passed anyway with only 51 votes. To my way of thinking, that ain't a good idea.