Q.Leaves Have Turned Purple , Gum Leaves
hi there, late summer , early autumn , i cut back some of my gum trees, canopy, there only 3 m tall, i am using them as privacy screening, i noticed recently that the leaves on the top side have turned purple, underside still green. is this a severe cold issue, phosphorous , poison or other related issue..? thxs in advance.

Certified GKH Gardening Expert
These should help pinpoint the issue:
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-leaves-turning-early.htm
https://www.gardeningknowhow.com/plant-problems/environmental/leaves-turning-reddish-purple.htm
https://www.gardeningknowhow.com/ornamental/trees/eucalyptus/eucalyptus-tree-diseases.htm