The $\gamma$-Liouville Brownian motion ($\gamma$-LBM) is the canonical diffusion process on a $\gamma$-Liouville quantum gravity ($\gamma$-LQG) surface, where $\gamma \in (0,2)$ is a parameter. The $\sqrt{8/3}$-LQG sphere, considered as (the isomorphism class of) a random compact metric measure space, has been proved by Miller and Sheffield (2021) to have the same law as the Brownian sphere, which in turn was proved by Le Gall (2013) and Miermont (2013) to appear as the scaling limit of a uniform random $n$-face quadangulation of the sphere as $n$ tends to infinity. This talk will present the main result of arXiv:2507.13269 establishing, for the heat kernel of the $\sqrt{8/3}$-LBM on the $\sqrt{8/3}$-LQG sphere, two-sided off-diagonal sub-Gaussian bounds which are sharp up to polylogarithmic factors in the exponential. This is joint work with Sebastian Andres (Technische Universität Braunschweig), Konstantinos Kavvadias (Massachusetts Institute of Technology (currently New York University)) and Jason Miller (University of Cambridge).