The 2 theories have epistemologically ("how to get knowledge") Distinct starting points, i underly here epistemological, not methodological i.e on level of phosophy of knowledge

GR considers or tests on hypothesis that the properties of matter and radiation(mostly radiation i.e light) are given i.e constant speed or state equations and describes in details the time space that is the results of these, then motion emerges i.e geodesic etc

QM takes hypothesis that spacetime is given i.e symmetry of Hamiltonian and studies properties of matter or particles (and their motion). Properties of particles are

emergent i.e spin

According to the incompatibility thesis*, the two approaches yield knowledge from different hypotheses. There is no. Middle ground as this would destroy tge knowledge generating process

*I will elaborate soon on a essay