Mapbox imagery is made of different layers: https://www.mapbox.com/help/mapbox-satellite-sources/
I contacted Mapbox support on December 2016, and here is the answer:
> Much of our [Satellite layer][1] is composited imagery, so we don't offer timestamps. Generally **Generally the imagery is between 6-18 months out, out**, though coverage varies. Here are a few interesting reads about how our Satellite team [prioritizes][2] and [purchases][3] new imagery for Mapbox Satellite.
> Glad you're loving our maps to help
> with OSM contributions! Have you seen
> these posts:
>
> - [https://www.mapbox.com/blog/streetlevel-photography/][4]
> - [https://www.mapbox.com/blog/announcing-id-v2/][5]
> - [https://www.mapbox.com/blog/mapping-3d-buildings/][6]
Also, there is a tool to report areas that need a refresh (e.g., too cloudy): [https://www.mapbox.com/bites/00240/#3/0.00/0.00][7]
And also:
> I've also recommend this [Remote Pixel][8] tool (that uses Mapbox, but also directs you to other providers). I've heard mixed results, but sometimes people love it.
[1]: https://www.mapbox.com/maps/satellite/
[2]: https://www.mapbox.com/blog/satellite-imagery-updates-telemetry/
[3]: https://www.mapbox.com/blog/three-million-km/
[4]: https://www.mapbox.com/blog/streetlevel-photography/
[5]: https://www.mapbox.com/blog/announcing-id-v2/
[6]: https://www.mapbox.com/blog/mapping-3d-buildings/
[7]: https://www.mapbox.com/bites/00240/#3/0.00/0.00
[8]: https://remotepixel.ca/projects/satellitesearch.html
