For all known deformation types of irreducible holomorphic symplectic manifolds (which I call K3, K3$^n$, Kum$^n$, OG$^3$, OG$^5$, the exponent being half the complex dimension), it is known that the map ${\rm Aut}(X) \rightarrow {\rm O}(H^*(X,\mathbb Z))$${\rm Aut}(X) \rightarrow {\rm Aut}(H^*(X,\mathbb Z))$ is injective.
For K3, K3$^n$ and OG$^5$ this follows from the fact that the map ${\rm Aut}(X) \rightarrow {\rm O}(H^2(X,\mathbb Z))$${\rm Aut}(X) \rightarrow {\rm Aut}(H^2(X,\mathbb Z))$ is injective (Beauville, Mongardi--Rapagnetta). For Kum$^n$, this is a theorem by Oguiso. For OG$^3$, this is known to experts.
Is this known in general?