I think it's because, like a first year writing student trying poetry, it tries a little too hard to make the lyrics coherent and storytelling in a script read from a page. A lot of real song lyrics have a whole lot of repetition, non sequiturs, and break grammar rules to fit the meter better

I mean, perhaps I should have made this more clear, but later models of GPT are leaps and bounds better than whatever suno is currently using.