One additional note, it does strongly react on temperature - I took another exposure in a fridge (about 5 degrees Celsius) and it is barely visible. The masterdark above was taken in about 23 degrees, but I suspect that sensor might had more than 30 degrees. Below is a single dark taken in a fridge.

That's very interesting, let me pass this on to Mabula.. I think a dark might fix this, not 100% sure though.

Ok, got word from Mabula. It's unfortunately not easy to solve, nor can it be solved at the moment with a dark. 🙁 Mabula does want to investigate if this could be addressed somehow, but that won't be something very soon.

Ok, I tried and dark can fix it in a huge degree but it would be much better to do not have it. It can wait however. Should I apply some dark frames for future investigation? It is connected with demosaic algorithm? Thanks.

Okay, I read this article https://petapixel.com/2017/02/23/fuji-cameras-produce-strange-purple-flaregrid-artifact/

correct me if I am wrong, but it seems that phase detection pixels are automatically multiplyed by 2 to compensate less light getting to them. In normal conditions it works well, but while taking dark frames they shouldn't do it like that, because they behave normally when there is't any light, but they values are still doubled, therefore I get such strange green grid in the phase detection pixels area.

Am I right? I do not want to correct it immadietally, I just want to understand how it works.

I have no experience myself with X-trans systems, but yes it would be nice if that could be switched off. Maybe something to ask the company as well? APP will try to correct these regions in the future, but it's not something we can support very soon.