since I see a lot of bs flying around, let me answer your question (as a CompSci major, an avid tech enthusiast and a 1440p monitor & PS5 combo owner):

• FOR NOW, it changes nothing. all people that had a 1440p monitor could've downscaled the PS5's 4K to 1440p with no drawbacks (as I did)

• FOR THE FUTURE, it means much more. having the GPU, interconnect and display controller render and transmit more than 4.5 million pixels per frame less (given we retain the same bit depth, framerate & banking) means that all of that processing power can be utilised towards improving the other big aspect, namely the frame refresh rate - currently we have 1080@120 & 4K@60, so a middle ground of 1440@120 or even 1440@144 is really appealing in the long run, since more and more people are gaming on monitors and not TVs

so bottom line, for the time being it isn't much of a difference, but it's paving the way for more combinations of resolutions and framerates