  Recently, the cosmological tensions, $H_0$ and $S_8$ in particular, have
inspired modification of both pre- and postrecombination physics
simultaneously. Early dark energy is a promising pre-recombination solution of
the $H_0$ tension, known to be compatible with the cosmic microwave background
(CMB). However, the compatibility of early dark energy, as well as general
early resolutions, with the CMB is no longer obvious if the late Universe is
also modified. Aside from cosmological parameters, the main channel through
which late Universe physics affects CMB observables is gravitational lensing.
We employed a new method of sampling functions using the Gaussian Process in
the Monte Carlo Markov Chain analysis to constrain the shape of the CMB lensing
potential. We obtained the early Universe (CMB) only constraints on the full
shape of the CMB lensing potential, with the late-time Universe being
marginalized over. It is found that CMB data prefers a lensing potential shape
that is $\Lambda$CDM-like at $80\lesssim L\lesssim400$ but with enhanced
amplitude beyond this range. The obtained shape constraints can serve as a
CMB-compatibility guideline for both late and early Universe model building
that modifies the lensing potential.
