Your comparators are the wrong way around?
$response = $sales->with('product')
->whereDate('created_at', '>=', $request->from)
->whereDate('created_at', '<=', $request->to)
->get();
Where between does not work because both start and end are 13/07/20 00:00:00
you can fix this by adding 1 day to the end date
$response = $sales->with('product')
->whereBetween('created_at', [
$request->from,
Carbon::parse($request->to)->addDay()
])
->get();