This is an excellent little book http://stevenbiggs.ca/about-thefigpig/
Steven Biggs is s hobby grower with lots of expertise.
I don’t know your grow zone, but it was obviously cold enough to damage the plant. Biggs is in grow zone 6. I am in 4. Both of us have to protect our plants in winter, generally by bringing them in to cold storage just before frost. My cold room is 5-7°C and dark. The tree will stay there until it starts to break dormancy and there is NO danger of frost. I bring it out into my workshop which has a south facing patio door. The tree will get scant water maybe twice in winter.
I also agree there appears to be some insect damage. Get your magnifying glass out and check underside of leaves. Or may also be some chlorosis.