The AOSP memory allocator is seldom the one used by OEMs.

Really? They're not using Scudo? The hardened_malloc used in GrapheneOS has a bunch of performance issues that were trade-offs against security. Every other major android distribution uses scudo as far as I know. Which OEMs are you thinking of?

Edit: Did some research after writing this? It appears that Samsung may be still using jemalloc, albeit a newer version than the one from the Android 11 days.