Yellowing leaves on only one branch.

picture of one lower branch outdoor buddha. The rest of the plant is very green & healthy looking without any yellowing on any other leaves or branches. I thought it looks like maybe Iron deficiency but don't know why wouldn't be elsewhere on plant. Any suggestions?? Please!! Haven't grown this strain before & in new area so different climate. Am in Canberra south of Sydney & highish altitude.

This website suggests this is a distinguishing trait of iron deficiency:

Iron deficiency can be identified when new leaves are completely yellow.

Aren't those newer leaves?