I know I am probably ABU but our neighbours have just got a trampoline for their three children. They have a big garden and have put it right next to the fence where we have our table and chairs. All I can hear is squeak squeak squeak of the springs.
I said to my DH would it BU to ask them to move it to the bottom of the garden and he said yes, very. Suck it up, far worse things than children playing outside. Their garden, their choice where to put it.
Our two DC have also got a trampoline but it’s at the end of the garden away from everyone’s houses, and doesn’t squeak.