if a Democratic triumvirate were to strip SCOTUS of jurisdiction (they can do that without a Constitutional amendment) then SCOTUS might declare that law unconstitutional
Easier and less ambiguous solution would be to expand the size of the court and appoint new justices (it has been done in the past). Add 5 more justices to the court, all hand-picked left-leaning nominees, and the fascist elements of the court could be indefinitely neutered without any legal ambiguity whatsoever.
Or just impeach and remove the problematic justices. Several of them already have plenty of evidence to support impeachment for corruption.