How does it appear that replacement isn't the true solution at this time? Because it would cost them too much money? The updated screen is available, they just don't want to have to incur the financial hit to replace that many of them. Replacements with the non-yellowing part have happened for some high-profile influencers and lucky follow-on customers who made appointments before the policy change.
But I suppose you're one of those people who actually think a firmware fix for this is possible, and that that's actually an option; in which case there's absolutely no point arguing with you.
The corrected part has been obtained by Tesla. The only way to fix this is via replacement. They are refusing to replace. A "firmware fix" is not possible. There's no further mystery here, unless you're part of the camp that believes that firmware is in fact magic.
Post 173 above.