no-unsafe-readonly-mutable-assignment failing to identify a ReadonlyShallow correctly

[danielnixon]

This is working:

        type Thing = { a: string };

        type OtherThing = { readonly a: string };

        // This is correctly inferred to be ReadonlyShallow        
        type ThingArray = readonly Thing[];
        
        // This is correctly inferred to be ReadonlyDeep
        type OtherThingArray = readonly OtherThing[];

        // ReadonlyDeep
        declare const a: OtherThingArray;

        // Flagged (ReadonlyDeep -> ReadonlyShallow)
        const b: ThingArray = a;

But this isn't:

        type Thing = { a: string };

        type OtherThing = { readonly a: string };

        // ReadonlyDeep
        declare const a: readonly OtherThing[];
        
        // Not flagged (it thinks readonly Thing[] is ReadonlyDeep when it should be ReadonlyShallow)
        const b: readonly Thing[] = a;

[danielnixon]

Looks like: https://github.com/eslint-functional/eslint-plugin-functional/issues/578#issuecomment-1475391803