This was shown on TV so may have been an episode of something, but ISTR it being a movie. I also remember it being in colour but it could have been B&W with colour added later.
The only details I remember was the use of what I think were cardboard cut-outs for humans transformed (drained? sucked dry?) by some alien influence, and the presence of some small black objects (small rocks? football sized or a little bigger) littering the area (desert/scrub IIRC, maybe South West US states).
It’s not Monolith Monsters or It Came From Outer Space as I’ve checked both.