Alex probably because it does it through the regular XBox Version and is therefore simpler to implement. There is a stronger distinction between PS4 and PS5 titles than XBox1 and XSX|S titles. Likely down to shared libraries/development environments etc. So for example a X1 title can recognise and take advantage of the fact it is running on an XSX, but a PS4 title can’t run natively on a PS5 - only via backward compatibility. This is also the reason some titles have had 120fps updates on XSX but not on PS5 yet. A PS5 native version is needed to take advantage of some features outside raw speed improvements.
There are native XSX/PS5 versions due next year, I’m waiting for those.