Kaledin–Lehn formality conjecture for polystable sheaves on K3 surfaces

Let $X$ be a projective K3 surface with a generic polarization $H$, and let $F$ be an $H$-polystable coherent sheaf on $X$. Kaledin–Lehn's formality conjecture. The differential graded algebra

$$\operatorname{RHom}^{\:\raisebox{3pt}{\text{\circle*{1.5}}}}(F,F)$$

is formal. The paper's abstract states that this conjecture is proved for complex projective K3 surfaces, so the claim is resolved.