When enabled on a device, lifts all Compatibility mode restrictions (features and limits) to Core.
Core-defaulting adapters always support the “core-features-and-limits” feature. It is automatically enabled on devices created from such adapters.
Compatibility-defaulting adapters may support the “core-features-and-limits” feature. It may be requested on devices created from such adapters.
For more details see WebGPU compatibility mode proposal