Wow, this YouTuber nails it right on the head -- the S7 charges noticeably slower on "regular" pucks (which unfortunately at the moment also includes integrated charging stands like my beloved Belkin 3-in-1 stand). Seems like it's USB-C or bust with these S7s nowDesFit did extensive testing on this issue. Looks like using the USB-C charger for the S7 is worth it at the moment.
That said, I've reached out through direct channels to contacts at Belkin to let them know about this and if anything can be done. Will update if I hear anything back.
As stated before, the 'power stack' for devices these days is so complicated, it's hard to tell what exactly is going on.