Am I crazy or are the models different on different plans?

Hi, I just downgraded from Pro 100 to Plus a couple hours back (renewal was due today) and the subscription got changed while I was in the middle of a task on Codex (because the 5h limit popped up when Plus kicked in). I saw a noticeable drop in quality for the task – it was preparing a deck of slides for an upcoming meeting, a task Astra has been nailing consistently for me recently. But then the output I got after the Plus plan kicked in was genuinely disappointing. Both plans were running Astra on medium. Is it possible that the version of Astra on Plus isn't as capable as the one on Plus?