  Gravitational waves provide a unique opportunity to test gravity in the
dynamical and nonlinear regime. We present a parametrized test of general
relativity (GR) that introduces generic deviations to the plunge, merger and
ringdown stages of binary-black-hole coalescences. The novel feature of the
model is that it can capture signatures of beyond-GR physics in the
plunge-merger phase. We use the model to provide constraints on the
plunge-merger parameters from the analysis of GW150914. Alarmingly, we find
that GW200129 shows a strong violation of GR. We interpret this result as a
false violation of GR either due to waveform systematics (mismodeling of spin
precession) or data-quality issues.
