Except that's not what it means. One-quarter of the way between red and orange refers to the color called Scarlet. Write scarlet in google and this exact phrase will pop up. It has nothing to do with PS5 being 25% faster.
Electronic Components Dealers lists various Micron GDDR5 and GDDR6 chips, pricing for 2,000 units. From these it can be seen that GDDR6 is currently much more expensive than GDDR5 at the moment. Goi...
Seems others have already convinced you why GDDR5 would be a bad idea, but just to add: GDDR5 (even 5X) would offer overall quite lower bandwidth per chip than 6. Stock GDDR5 at 8Gbps and, say, 1250MHz, would only get you about 40 GB/s. On a 384-bit bus, that's a memory bandwidth of 480 GB/s. That seems impressive on its own, but not when there is already speculation Scarlet could have around 672 GB/s of bandwidth going with GDDR6 (1000MHz, 14Gbps, 384-bit bus like the X).
If Sony is pushing the GPU clock as high as it can go, GDDR5 would potentially leave it bandwidth-starved. Plus while it's cheaper than GDDR6 right now, it won't remain that way; GDDR5 only had 2 of the Big 3 memory manufacturers onboard, while 6 has all three (Samsung, Micron, SK Hynix) involved. That'll lead to much bigger volumes of it produced over time which'll drive the costs down. As GDDR5 production is scaled down, it'll end up being mainly smaller plants in places like China producing reduced quantities of it for things like hardware support of legacy devices, and the such.
People have this weird assumption that next gen consoles gonna have some powerful, advanced RT solution on par with RTX. RT was clearly a late decision fueled by RTX cards. So I wouldn't expect anything fancy in that department but rather something that just ticks the RT checkbox on the feature list.