Sos what is happening?

What is happening with these leaves on our Queens Land Bottle Tree? We have had this tree in our living room and it survived the winter but some branches died off… and all the leaves that drop have this weird coloration to it? Is there something I am doing wrong? It has grown a solid 8 inches in the year so I don’t think I’m killing it but whatever this is I would like to know if I’m the reason and it can be prevented or if it is normal! Any advice would be greatly appreciated