Dev slump.

For me dev slump is usually feeling overwhelmed and that leads to being unmotivated.

My solution usually involves, go slow, way slower than usual. "Make function... that takes a thing. well that worked..." rather than try to think of everything at once.

Also get some easy tasks broken out and do those (even unrelated). That tends to get me going, feeling productive, then I start to approach the harder stuff that was maybe more demoralizing.