user.service.ts

@Injectable()
export class UserService {
  private cached$: ReplaySubject<any> = new ReplaySubject(1, 2500);

  constructor(private _client: HttpClient) {}

   public findAll(id): Observable<any> {
     const req = this._client.get(`https://reqres.in/api/users?page=${id}`).pipe(
       tap((data) => {
         this.cached$.next(data);
       })
     );

     return race(this.cached$, req);
   }
}