Sony may boast that 'Play Has No Limits', but there will be a limit to the PlayStation 5 if you try to game at 1440p later this month. According to IGN Italia, Sony has confirmed that its next-generation console will not support the resolution that is popular with PC gamers, for some reason.
https://www.notebookcheck.net/PlayStation-5-Sony-confirms-that-its-next-generation-console-will-not-support-1440p-gaming.502580.0.html
Well, that was expected, where half of the trick is the Sony variation of DLSS and upscaling.
1080p->4k,
1440 would bring only problems since most of TVs are either 1080p or 4k.
What you are saying is not valid for PS5. Actually Demon Souls will be upscaled from 1440p to 4K in performance mode. So if this is seemingly not a problem to do, why not supporting native 1440p? :-\