It matters most with whom the courts are staffed, @Kamaji
Yes, it does, but each nominee should be given fair consideration, and his or her record taken into account, and the mere fact that he or she was appointed by a democrat president or a republican president should not be the determinative factor. This is particularly the case if the individual has already been serving as a judge on either another federal court, or on a reputable state court, and his or her conduct, in particular how and to what extent his or her personal political preferences influence his or her rulings, can be taken into account.
This is another perfect example of "don't do it unless one wants the opposition to do it back the next time they have sufficient power." If all of Biden's nominees were rejected by the republicans simply because Biden appointed them, then the democrats will play that game right back at us when the shoe is on the other foot.
We got lucky as hell that McConnell was able to force enough party unity to get Gorsuch, Kavanaugh, and Barrett onto the Supreme Court, and was able to shepherd another 200 plus Trump nominees onto the lower courts. If we pull such a short-sighted litmus test, the process will become disfunctional and the only way new judges will ever be appointed is during those few periods when one political party has both the White House and a commanding majority in the Senate. That is a recipe for making sure that only the most partisan judges ever get on the bench, and that will inevitably damage the courts.
That is not a game that should be played lightly.