When there is split control of Congress, there are ridiculous things, such as using the debt ceiling as a hostage, which don't fit the model of standard opposition. Taking the country hostage and threatening to shoot it is reasonably thought to be beyond the pale, though if you negotiate in good faith with those who try it... shruggy.
But right now Mitch McConnell can't do anything the Democrats don't let him do, allowing for the fact that in any reasonable political system, the minority has *some* ability to gum things up a bit. This doesn't make Mitch good - Mitch is very bad - but really every time I see someone complaining about Mitch stopping the Senate from doing things, I want to scream.
Chuck Schumer runs the Senate. The rules are what they are because a portion of Democrats want the rules to be that way. That isn't necessarily Chuck's fault or Biden's fault, but it isn't Mitch's fault. When Mitch didn't like what Demcorats in the minority were doing, he changed the rules.