brings back the good ol' single Alt for preview access

hackContentAccess.ub.js

function ubiquityLoad_hackContentAccessForPreview(U){//function cmd_
  const {prefs} = Utils, Shift = 1, Ctrl = 2, Alt = 4, Meta = 8;
  U.panel.addEventListener('popupshowing', function hack(){
    var orig = prefs.get('ui.key.contentAccess');
    Utils.listenOnce(this, 'popuphidden', function restore(){
      prefs.set('ui.key.contentAccess', orig);
    });
    prefs.set('ui.key.contentAccess', Alt);
  }, false);
}