It is obvious in the skies that you have a lot of noise and obvious lines between some areas. That shows that video quality is poor. There is no 100% solution, but without some serious denoise tool, this will be very hard for you. Try Neat video cleaner, and you should manually adjust your camera. Avoid high ISO, exposure etc. And even when you have good phone I think that phones are still phones. Do not waist money, and by proper DSLR or prosumer camera from Sony.
Well I think without some real good noise cleaner tool you will struggle more and more. Try Neat Video noise cleaner.