Makes sense why it's recording at 720p. Didn't receive a Pro patch hence running in PS4 BC mode on PS5. Basically emulating how the PS4 would run to the point that even the capture software is emulating how PS4 would record vids.
A simple way to confirm this is to run other games that haven't received a Pro patch... Like The Order 1886, Bloodborne, Driveclub...
Or try to capture a native PS5 game and see if it's still 720p.