2GIG Plan - only 600-650 wifi through gateway

Short version:  yes, it's probably just a radio limitation, though it's likely a combination of the XB7 and the phone.  A laptop might do better, especially one with a higher end WiFi adapter.  There's a good chance an XB8 or 3rd party WiFi 6e gear would do better.

At least it's just a WiFi issue with a phone and your desktop is going full speed.

5G performance from a phone company tower doesn't really have anything to do with WiFi performance.

The XB7 is a WiFi 6 device.  How fast WiFi 6 can go depends on the hardware.  Not all radios are the same.  Most clients (phones, laptops, etc.) have a 2 stream radio.  Also having support for 160MHz wide channels makes a big difference.  A lot of WiFi 6 devices don't support 160Mhz channels and can only use up to 80Mhz.  For a 2 stream radio the maximum theoretical throughput on an 80MHz channel is 1200Mbps.  Getting half of that with a phone isn't unusual.  You never get close to the max to begin with.  If you get 75% you're doing really well and 2/3s is considered normal for a laptop.  Half on a phone is nothing to freak out over.  I'm not sure what the exact specs are on an Samsung Galaxy S22 Ultra, but Samsung says 2.4Gbps WiFi is only available with WiFi 6e.  That basically means 2 streams and 160MHz channel width on WiFi 6e.  That doesn't work on WiFi 6, so it's probably 2 streams and 80MHz channel width on the 5GHz band.  That would limit it to 1200mbps maximum theoretical bandwidth.  600 is about half, and that's not unreasonable.

WiFi 6e (need an XB8 or 3rd party WiFi equipment) is largely the same as WiFi 6 except for the 6GHz band support.  The 6GHz band is much wider than the 5Ghz & 2.4Ghz bands, and 6e radios are much more likely to support 160MHz channel width at least in the 6GHz band.  You're also less likely to suffer from interference from neighbors on the 6GHz band since there a lot more channels available.  The one down side is it doesn't go through walls, floors, and ceilings quite as well as 5GHz.

@user_9932b8 - Thank you for sharing your speed concerns with the community! I see some feedback on your post, and wanted to check in on things. Are you still experiencing speed issues at this time? Did the previous suggestions help?