Well I think it's obvious that some change was intended, but airlines have been known to use wording that conveys a different meaning than intended.

When I first read it, I just assumed it meant that if you accepted an upgrade offer after your initial purchase, then that would be considered in the upgrade calculus whereas it might not have before.
(Though I can't say for sure whetherit wasn't.)

I'll note that this language still exists on the page, and it isn't noted that this is no longer true in 2024, where other bullet points have been marked as no longer applying.