Massive star cluster seeds form by gravo-turbulent flows rather than magnetized collapse

High-mass stars form in protoclusters, where gravo-magnetic processes shape massive star-forming clouds and clumps to be elongated preferentially perpendicular to magnetic fields. Yet it remains unclear whether magnetic fields still govern the formation of smaller-scale ($\sim$1000 au) condensations in massive protoclusters, which are crucial for understanding the stellar initial mass function and multiplicity. Here we report the first statistical evidence that the condensation elongation exhibits a preferentially more parallel alignment with magnetic fields at $\sim$1000 au scales, based on high-resolution data from the largest dust polarization survey toward 30 massive star-forming regions with the Atacama Large Millimeter/submillimeter Array (ALMA). Our clustered massive star formation simulations reveal that this more parallel alignment is exclusively observed in initially super-Alfv\'{e}nic (turbulence dominates magnetic fields) models. In contrast, initially sub-Alfv\'{e}nic (magnetic fields dominate turbulence) models distinctly exhibit a more perpendicular alignment. These findings offer compelling statistical evidence that the formation of small-scale condensations is governed by turbulence rather than magnetic fields in the context of clustered massive star formation, contradicting the prediction of classical magnetically regulated models. Moreover, turbulence imposes a preferential misalignment between the magnetic field and rotation axis of condensations, which can potentially reduce the magnetic braking efficiency, facilitate the formation of large protostellar disks, and allow disk fragmentation to occur.