You should be aware of how the Return to Home (RTH) functions.
Anytime the aircraft looses control signal, it will pause in flight, then increase altitude to the preset RTH altitude that you set on the controller. The aircraft then rotates to face the home coordinates, raise the landing gear and flies back toward the home point.
This is IMPORTANT: If it regains signal from the controller, it will stop and hover until you provide input on the sticks. If you don't have video signal you may not realize it has gone into hover. If you do nothing it will hover until the battery gets low and then it will auto-land right where it is.
The best practice would be to always select Home Mode in this situation and wait until you have visual contact. Then switch to Angle mode and land manually.
I have seen many reasons for the aircraft to loose signal.
1. A sudden strong RF signal which interferes with the 2.4 GHz control signal.
2. Flying behind a large structure or trees.
3. Sudden change in weather such as fog, snow or rain which blocks the RF signal.
4. Flying too far away at a low altitude.
5. Running the battery too low on the controller.
You must anticipate conditions which might trigger RTH. I saw a pilot fly low under tall trees that were a great distance away. He wanted a "Forest shot". He was watching the camera view. When the aircraft got too far into the tree cover it lost control signal, then executed an RTH which sent it straight up into the tall upper limbs of a tree. Nearly destroyed the drone and camera.
Another guy flew behind a 200' tall building but he had the RTH set at 100'. You can guess what happened.