Whether life could survive is entirely orthogonal to my point, and sneaky life surviving that we can't even see is exactly what I said could still be on Mars. What can't be on Mars is life with stalks (it may not sound like much to a Earth-bound human in 2021, but that's actually quite sophisticated for life) that grows macroscopically over the course of just a few days. There'd be evidence of their metabolites, probably color and spectra changes like Earth's greenness as something uses sunlight, all kinds of things. Macroscopic plants are way too much to claim on the basis of a few photos. I mean, if nothing else, we ought to see lots of them.