Really don't need to be overly concerned over having a P2 (80+ Platinum rating PSU) instead of a T2 (80+ Titanium rating PSU) - both are very high quality, and there's
very little difference between them.
Facts: There's only a 1% difference in
minimum efficiency between Titanium and Platinum at full load (90% vs 89%).
There's only a 2% difference in
minimum efficiency at 20% load (92% vs 90%).
There's only a 2% difference in
minimum efficiency at 50% load (94% vs 92%).
That's pretty much negligible for the vast majority of users except maybe a few of the world's top ranked LN2 overclockers, and even then it's likely not a big deal.
The only other 'difference' to note is that 80+ Titanium rated PSUs are guaranteed at 90% minimum efficiency at 10% load, while ALL other 80+ rated PSUs only begin their efficiency guarantees at 20% load, which is really of zero concern for overclocking.
That's it.
As to why EVGA are packaging these quality high efficiency PSU's with the 3090TiKP - I'm assuming they want to make sure owners have sufficient wattage and clean power to run them at peak performance and not have them under-perform because of insufficient power delivery or inferior quality power delivery.