It's missing SU-BEAMFORMER-CAPABLE but that likely is not an issue. The iphone 10 also is not BEAMFORMER capable but can still connect at 866 mbps for tx as reported by the r7500v2. I'm not an expert on VHT or wifi radio but I'd guess that lack of beamformer capability would only affect the data rate for uploading from the s7 (i.e. the rx link bitrate reported on the r7500v2).
Before you go too far troubleshooting, I have seen device link speeds (both tx and rx) change up and down depending how much the device is being used. You can use a command like iw dev wlan0 station dump | grep bitrate on the r7500v2 from a ssh session to keep an eye on them.
If your up to it, using a program like iperf3 on your s7 to send/recieve data from a laptop (also running iperf3) connected to the lan of the r7500v2 by wire will give you a better feel for the actual data transfer rates up and down from the s7.
One thing that caught my attention is that all your devices support MU-BEAMFORMING. I've seen suggestions to disable MU beamforming on routers as it can cause slowdowns. I've never experienced any as I only have one device that is MU beamforming capabale and MU beamforming is only relevant when multiple clients and the router support it. That said, perhaps try connecting the s7 to the r7500v2 5GHz with no other devices on 5GHz while observing the reported link rate (or better an iperf3 test) from your laptop connected via to the r7500v2 lan (i.e. ethernet wire).
It's possible to disable MU beamforming on the r7500v2 (example here). There may be easier ways to do it but I haven't stumbled accross one yet. If MU beamforming is causing you issues, then trying the hostapd settings I mentioned in my post above might help.
Beyond this, I don't have ideas about why your observing slower link rates with your s7.
Good luck.