You’re right. If life really does boost entropy production, then in principle it should leave a footprint in how planets handle energy. The tricky part however, is telling apart what's due to biology versus what's just weather, geology, or atmosphere.

Of course, to notice something like this from such vast distances, the energy transformations would have to be happening on a very large scale. So, it's possible life is out there, but just not at a scale on those planets that our current instruments could pick up.

By any chances, do you have any good reading references for this: "I have seen this idea somewhere" .. I am genuinely curious to read more on this.