As for no-extend-native, this rule currently doesn't report any errors in the following code:

/* global FinalizationRegistry, WeakRef */

FinalizationRegistry.prototype.foo = bar;
WeakRef.prototype.foo = bar;

It will start reporting this code, but not before the next ESLint major version when we will upgrade the globals package to ^13 or above.

The same applies to a configuration where the new es2021 environment (which contains FinalizationRegistry and WeakRef) is enabled.

So, regardless of user configuration, the no-extend-native rule will not disallow modifying FinalizationRegistry and WeakRef prototypes until ESLint v8.0.0.

This is in line with a similar decision in #11803 for new BigInt globals, where it was seen as a breaking change, and thus postponed for v7.0.0 (though, for most users the change probably happened before v7.0.0, because globals added BigInt globals in a minor version of the package, and we have ^ dependency).

Marked as breaking for Update 2: upgrading globals package, which would cause no-extend-native to report more errors.