User manual page 47:
"Height is restricted to 16 feet (5 meters) when the GPS signal is weak and Vision System is activated. Height is restricted to 98 feet (30 meters) when the GPS signal is weak and Vision System is
inactivated."
If there is no visible pattern on ground or not enough light, it will not be in VISON mode but ATTI. Also if you disable vision system you can go higher but it means you will have no horizontal stabilization. Making observation in ATTI mode is really not that easy if there is any air flow. Easy is to activate the video recording, just fly over and then check the video after safely landing.
Use prop guards is highly recommended till you are confortable.