Weird behavior with generics in generic tuple types #41857

TypeScript Version: 4.1.2

Search Terms:
Tuple generics
Generics in function tuple types

Code

type Act<S extends object> = {
  act<I extends ((shape: S) => object)[]>(
    ...intentions: I
  ): Act<S> & S & UnionToIntersection<ReturnType<I[number]>>;
};

Expected behavior:
Once S is provided, The 'act' function should automatically infer the specific type of S, which is constant for every element of the tuple type (I), and make the 'shape' parameter typesafe.
This behavior works correctly when:

// Without tuple type
type Act<S extends object> = {
  act<I extends object>(
    ...intentions: ((shape: S) => I)[]
  ): Act<S> & S & I;
};

Actual behavior:
S is inferred as object, instead of its specific type. The return type is inferred correctly.

Playground Link: https://www.typescriptlang.org/play?#code/C4TwDgpgBAqgdgSwPZwCpIJJ2BATgZwgGNhk4AeGAPigF4oAKGKCADxzgBN8oBDOEFAD8jMAC5YASjo0AbkgScoEuBFl5pbDt0YAoKFHFQEcAGZ4oGXdNpyFnfcMuOVavAG5Hu0JCgBBEnIAZRZ2CC4eJAAjACtiYBp6AG9HXkCMUO0eBgZ8AAteSAkgmxpouJJJAG0AXSoGRwMAOhaTDlIUfAkrA0kJAOBgmgAyKBDR+DJ0LBwCeLJyACUIYABXXDRwCHIMKrhVgFsovDqqTwBfdyA

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