It's extremely suspicious this coincided with a massive battery recall that caused unexpected shutdowns.

I'm not sure if I follow you here, particularly the use of "extremely suspicious", which makes me think that you believe something underhanded is going on. If so, would you just come out and say it? Innuendo doesn't generally promote useful discussion, and it's even harder on an online forum. Was this something you were thinking about when you wrote your initial comment? If that's not the case, please forgive me. I assumed your initial comment was a legitimate question, and answered in good faith.

If they are related (and perhaps they are, I wasn't thinking about the recall when I wrote my comment), do you think it's unreasonable for engineers at Apple to try to prevent unexpected shutdowns? I would think it would be unreasonable not to, once they saw the impact it was having on user experience. And that's besides improving the battery. The amount of engineering that goes on with respect to power and performance management is incredible, and attacking these types of problems from multiple angles is expected, particularly when you're looking to eek out even more performance in something that's already been through years of optimization iterations.

To be explicit I think this was done to limit the scale of the recall. I think the design flaw exists in all the phones not just the subset they identified.

Apple knew the peak draw of their SoC (they designed it). And they knew the capabilities of the battery. Under sizing the battery is exactly what I would call a design flaw.

This certainly seems to be the case from my experience. Same thing they did for previous recalls on MacBooks.