  We present JWST/NIRCam observations of a strongly-lensed, multiply-imaged
galaxy at $z=6.072$, with magnification factors >~20 across the galaxy. We
perform a spatially-resolved analysis of the physical properties at scales of
~200 pc, inferred from SED modelling of 5 NIRCam imaging bands on a
pixel-by-pixel basis. We find young stars surrounded by extended older stellar
populations. By comparing H$\alpha$+[NII] and [OIII]+H$\beta$ maps inferred
from the image analysis with our additional NIRSpec IFU data, we find that the
spatial distribution and strength of the line maps are in agreement with the
IFU measurements. We explore different parametric SFH forms with Bagpipes on
the spatially-integrated photometry, finding that a double power-law star
formation history retrieves the closest value to the spatially-resolved stellar
mass estimate, and other SFH forms suffer from the dominant outshining emission
from the youngest stars, thus underestimating the stellar mass - up to ~0.5
dex-. On the other hand, the DPL cannot match the IFU measured emission lines.
Additionally, the ionizing photon production efficiency may be overestimated in
a spatially-integrated approach by ~0.15 dex, when compared to a
spatially-resolved analysis. The agreement with the IFU measurements points
towards the pixel-by-pixel approach as a way to mitigate the general degeneracy
between the flux excess from emission lines and underlying continuum,
especially when lacking photometric medium-band coverage and/or IFU
observations. This study stresses the importance of studying galaxies as the
complex systems that they are, resolving their stellar populations when
possible, or using more flexible SFH parameterisations. This can aid our
understanding of the early stages of galaxy evolution by addressing the
challenge of inferring robust stellar masses and ionizing photon production
efficiencies of high redshift galaxies.
