It's meant to protect apps against their own bugs. It's an improvement to be enabled by default and disabled for the few apps where it's an issue.

> What is the point of this hardening feature if you got to disable it ?

It doesn't have to be disabled. Most users are saying OsmAnd runs fine for them with the default of hardened_malloc being enabled. There was no need to disable the other hardening features. A subset of users are experiencing slow performance in the OpenGL rendering mode with hardened_malloc enabled. It's likely due to the implementation in the app doing something quite inefficient which hasn't yet been identified. The hardened_malloc configuration in GrapheneOS is heavily oriented to security and has more overhead than the lite configuration. We could offer a performance vs. security mode for it but it usually makes no major difference and has a toggle for any case it does.

> Anyway it also requires the app to be able to even run on a rom that doesn’t respect play integrity.

?? GrapheneOS does respect horrid play integrity (it provides basic integrity only).

Not that this has any bearing on how an app runs performance-wise.