  Based on the canonical quantization of $d\geq2$ dimensional General
Relativity (GR) via the Dirac constraint formalism (also termed as 'constraint
quantization'), we propose the loss of covariance as a fundamental property of
the theory. This breakdown occurs for the first-order Einstein Hilbert action,
whereby besides first class constraints, second class constriants also exist
leading to non-standard ghost fields which render the path integral
non-covariant. For the Hamiltonian formulation of GR, only first class
constraints exist, however, the loss of covariance still happens due to
structures arising from non-covariant constraints in the path integral. In
contrast, covariance is preserved when constraint quantization is conducted for
non-Abelian gauge theories, such as the Yang-Mills theory. Hence, we infer that
the breakdown in space-time is a property of GR itself (for $d\geq2$
dimensions). Covariance is recovered and quantization and perturbative
calculations are possible in the weak limit of the gravitational field of these
actions. Hence, we further propose that the breakdown of space-time occurs as a
non-perturbative feature of GR in the strong limit of the theory. These
findings are novel from a canonical gravity formalism standpoint, and are
consistent with GR singularity theorems which indicate breakdown at a strong
limit of the field. They also support emergent theories of spacetime and
gravity, though do not require thermodynamics such as entropic gravity. From an
effective field theory view, these indicate that new degrees of freedom in the
non-perturbative sector of the full theory are a requirement, whereby
covariance as a symmetry is broken in the high energy (strong field) sector.
Our findings are also consistent with the recent resolution of the information
loss paradox in black holes.
