If a checkbox is unchecked when its form is submitted, there is no value submitted to the server to represent its unchecked state (e.g. value=unchecked); the value is not submitted to the server at all.
You should use the has method to determine if a value is present on the request. The has method returns true if the value is present on the request.
Try something like:
$team->financialsupport = $request->has('financialsupport');