Google uses drone imagery for some cities, San Francisco being one of them, using different angles to create the 3D model of the city, and satellite imagery for the rest of the planet. It's exactly what this company is doing. From what I can see, Google Maps also uses different textures depending on the viewing angle.
I don't have any idea what they are using there, but they do pull in a lot of aerial photos from the U.S. government. Those photos are (largely?) taken from piloted planes though.
I'm not sure why you think it's lower res. It looks about equivalent to me. The trees look a bit odd in Google maps, but the quality of the building windows and cars looks about the same.
Here's a more nuanced theory: The building fronts, cars, etc look great because they are from street view. The roofs, treetops, etc, look terrible, because they are from satellite.
The roofs, treetops, etc. look terrible because the depth data is significantly lower resolution than the photos. This causes the deformed polygons you're seeing... The actual resolution of the photos of the roofs/treetops are just as good as everything else, they're just stretched over bad 3d data.
Check out https://www.google.com/maps/place/San+Francisco,+CA/@37.7623... and rotate the image. Check out the trees to see the seams of the different pictures used to create the textures/models.