  In light of the very recent updates on the $R_K$ and $R_{K^*}$ measurements
from the LHCb and Belle collaborations, we systematically explore here imprints
of New Physics in $b \to s \ell^+ \ell^- $ transitions using the language of
effective field theories. We focus on effects that violate Lepton Flavour
Universality both in the Weak Effective Theory and in the Standard Model
Effective Field Theory. In the Weak Effective Theory we find a preference for
scenarios with the simultaneous presence of two operators, a left-handed quark
current with vector muon coupling and a right-handed quark current with axial
muon coupling, irrespective of the treatment of hadronic uncertainties. In the
Standard Model Effective Field Theory we select different scenarios according
to the treatment of hadronic effects: while an aggressive estimate of hadronic
uncertainties points to the simultaneous presence of two operators, one with
left-handed quark and muon couplings and one with left-handed quark and
right-handed muon couplings, a more conservative treatment of hadronic matrix
elements leaves room for a broader set of scenarios, including the one
involving only the purely left-handed operator with muon coupling.
