The report came from IGN Italy, which claims the information came directly from Sony. Not having support for 1440p output would mean one of two things. Those using screens with that resolution will either be getting their game upscaled from Full HD or downscaled from 4K.
On one hand, it’s not difficult to see why Sony came to this decision, if it is indeed true. In the previous console generation, Full HD was the standard before the mid-generation, upgraded versions of the consoles like the PS4 Pro showed up. And on those, the focus suddenly shifted to 4K, forgoing 1440p altogether. The middle-ground resolution is also not usually a resolution that TVs support. But on the other, it means those that use a single display for their gaming PC and console can’t have the best experience for both simultaneously. And it’s a strange situation either way, since the PS5 is powerful enough to support 4K 120fps output anyway. (Source: IGN Italy)