Unless there are other facts not mentioned, this is pretty straight forward.
The law allows a property owner with a neighbours tree overhanging the property line to trim the tree to the property line without reference to the owner of the tree. The trimming is at the cost of the affected owner.
Since this overhang is over common property, only a simple majority of the committee is required to authorise this action, under the requirement to maintain the property.
I know trees are an emotional issue, with some people hating them if they shed leaves, fruit and flowers, and others love them for the environmental benefits they bring.
Unfortunately for both sides, neither argument holds for strata. It’s the will of the majority.