There is nothing that allows it. The Constitution is not something that can be twisted to suit the circumstances any time you want. The Constitution is specific in identifying the circumstances under which a super majority is needed - treaties, impeachment trials, amendments, veto overrides. The suggestion that Congress can pick and choose what else to set that barrier at is ridiculous. What if the Senate said that presidential appointments needed unanimous approval? Or if the House decided that a super majority was needed to impeach someone to begin with? Would you say that was in keeping with the founders view of the Constitution? Of course not. If the Founding Fathers had meant for tax increases to require a super majority then they would have said so.
In order to be found “unconstitutional” it would have to violate some article of the constitution. You’re talking about a Provision that would further limit the power of the Federal Govt as opposed to extending its power.