  We present observational evidence of the impact of triaxiality on radial
profiles that extend to 40 Mpc from galaxy cluster centres in optical
measurements. We perform a stacked profile analysis from a sample of thousands
of nearly relaxed galaxy clusters from public data releases of the Dark Energy
Survey (DES) and the Dark Energy Camera Legacy Survey (DECaLS). Using the
central galaxy elliptical orientation angle as a proxy for galaxy cluster
orientation, we measure cluster weak lensing and excess galaxy density
axis-aligned profiles, extracted along the central galaxy's major or minor axes
on the plane-of-the-sky. Our measurements show a $\gtrsim2-3\sigma$ difference
per radial bin between the normalized axis-aligned profiles. The profile
difference between each axis-aligned profile and the azimuthally averaged
profile ($\sim\pm10-20\%$ along major/minor axis) appears inside the clusters
($\sim0.4$ Mpc) and extends to the large-scale structure regime ($\sim10-20$
Mpc). The magnitude of the difference appears to be relatively insensitive to
cluster richness and redshift, and extends further out in the weak lensing
surface mass density than in the galaxy overdensity. Looking forward, this
measurement can easily be applied to other observational or simulation datasets
and can inform the systematics in cluster mass modeling related to triaxiality.
We expect imminent upcoming wide-area deep surveys, such as the Vera C. Rubin
Observatory's Legacy Survey of Space and Time (LSST), to improve our
quantification of optical signatures of cluster triaxiality.
