Discrimination is not as difficult to figure out. It is in your face only if you are willing to see it. DOS and/or USCIS ever since 2008 have actively worked their way through all ROW backlog in PERM I-140 and 485 and later on in CP too. They have consistently prioritized everybody else of India and China backlogs. They have interpreted laws in a manner that has hurt EBIC e.g. in the old days they would interpret spillover vertical until courts forced them to do spillover within category before they could give visas to next category same country. Even right now they have been interpreting country limit across EB and FB and conveniently giving away more visas to non backlogged countries just to starve EB-IC. On top of all of this they have plainly wasted thousands of visas even in non-covid years. Now when COVID presents a huge opportunity then they are wasting not one or two thousands but 50-100 thousands. This is clear bias.
So other than country cap this bias has significantly hurt EBIC.