Light flying strangely up and down in SW of Las Vegas.

i saw some light flying like a U letter from north to south, than a bit east, than north again, than south, than west, than north.and back, and some other strange movements what a drone, baloon, rocket, aeroplane ,helicopter ,or any known object can not fly like that for like 20 seconds.  like a swing with a children on it doing a U movement/fly or whatever.  they was moving on the sky not flying,they go up and down,and up and down.
this happened in the sky in a big area like a 50 sqare mile.Helicopters can not fly/move like that.
like up and down, and when they was mooving the light become stronger a bit, and bit lighter.
same like when they lost the gps signal and they was trying to catch the signal, just i don't see any sense why they swas doing that U kind of fly on the sky i saw this from Las Vegas like 3 weeks ago(i cant tell you exact date),was before midnight,i was goint to eat tacos and that taco place close at midnight,so was like 11:30 and was on the sky on the south west part of Las Vegas, somewhere like 30 miles outside the city or maybe more.  The light was flying in this U kind of movements for like 20 seconds than was like when you of the light and didn't see them anymore.
Thank you to listening my story!