  Spontaneously broken symmetries are at the heart of many phenomena of quantum
matter and physics more generally. However, determining the exact symmetries
broken can be challenging due to imperfections such as strain, in particular
when multiple electronic orders form complex interactions. This is exemplified
by charge order in some kagome systems, which are speculated to show nematicity
and flux order from orbital currents. We fabricated highly symmetric samples of
a member of this family, CsV$_3$Sb$_5$, and measured their transport
properties. We find the absence of measurable anisotropy at any temperature in
the unperturbed material, however, a striking in-plane transport anisotropy
appears when either weak magnetic fields or strains are present. A symmetry
analysis indicates that a perpendicular magnetic field can indeed lead to
in-plane anisotropy by inducing a flux order coexisting with more conventional
bond order. Our results provide a unifying picture for the controversial charge
order in kagome metals and highlight the need for microscopic materials control
in the identification of broken symmetries.
