How to resolve the question of typescript generic function

Question

class Context {}

declare function call<C>( method: ( value: unknown, context: C ) => unknown ): any;

declare function fn1<T>( value: T, context: Context  ): Promise<T>;
declare function fn2( value: unknown, context: Context ): unknown;

call( fn1 );
call( fn2 );

I have code above, and you can also view it in Playground.

call( fn1 ) triggered error message:

Argument of type '<T>(value: T, context: Context) => Promise<T>' is not assignable to parameter of type '(value: unknown, context: unknown) => unknown'.
  Types of parameters 'context' and 'context' are incompatible.
    Type 'unknown' is not assignable to type 'Context'.(2345)

But call( fn2 ) works well.

Is it because fn1 is a generic function and why?