Sunburn or what?

[miki_cap]

Hi everybody. I hope someone can help.
There are these spots on my neofinetia leaves.
At the beginning I thought they were sunburns and in fact I left it under too much sun light at the beginning of the Summer to stimulate blooming.
A couple of months ago I moved it to a shaded side of the garden (norht-east) where it doesn't get any direct sun but new spots are forming anyway. Initially they appear like lighter green areas, often on the edge of the leaves but then they gradually become brown and dry.