  Planets orbiting M-dwarf stars are prime targets in the search for rocky
exoplanet atmospheres. The small size of M dwarfs renders their planets
exceptional targets for transmission spectroscopy, facilitating atmospheric
characterization. However, it remains unknown whether their host stars' highly
variable extreme-UV radiation environments allow atmospheres to persist. With
JWST, we have begun to determine whether or not the most favorable rocky worlds
orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8-5.2
micron JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3x
Earth's insolation) super-Earth GJ 486b (1.3 R$_{\oplus}$ and 3.0
M$_{\oplus}$). The measured spectrum from our two transits of GJ 486b deviates
from a flat line at 2.2 - 3.3 $\sigma$, based on three independent reductions.
Through a combination of forward and retrieval models, we determine that GJ
486b either has a water-rich atmosphere (with the most stringent constraint on
the retrieved water abundance of H2O > 10% to 2$\sigma$) or the transmission
spectrum is contaminated by water present in cool unocculted starspots. We also
find that the measured stellar spectrum is best fit by a stellar model with
cool starspots and hot faculae. While both retrieval scenarios provide equal
quality fits ($\chi^2_\nu$ = 1.0) to our NIRSpec/G395H observations, shorter
wavelength observations can break this degeneracy and reveal if GJ 486b
sustains a water-rich atmosphere.
