Well, they added new effects (patch notes) but both systems had some performance issues in some cases. So if the res drops more on PS5 (as it is dynamic) it should just drop because the performance would otherwise be worse (simple as that).
But after all, this is just a quick patch to get rid of the worst performance problems and tearing. Lowering bottom resolution target is not really an optimization, just a quick fix.
After all it should be like in the other titles, the xbox is underperforming. Take measuring device of your choice behind the xbox and you will see that the system does not draw much power at all. This just indicates the soc is not really under load and is idling around. MS must really fix their tools, so developers can reach max load on the chip.
PS: The low power-consumption is just and indicator that something is wrong and does not prove anything. But it is really odd that the power-consumption is as low as it is in third party games. Even BC games draw more power than native third party games.
I'm wondering if we can really compare power draw between the PS5 and the XSX since they handle it differently.