If you click the info (i) in the bottom-right, you'll see that the basemaps are ...

kanbara on March 10, 2017 | parent | context | favorite | on: Planet Explorer Beta

If you click the info (i) in the bottom-right, you'll see that the basemaps are from OSM and MapBox but the raster satellite imagery is from Planet's satellite constellation.

lucb1e on March 10, 2017 [–]

Ah, I had missed that icon, thanks!