What Maori or Kupe ability takes away Production? Did I miss something?
Edit. Oh, you built something on the rainforest, then you will lose the bonus production.
In general the tooltips for builder actions are usually wrong, that is not the only case. Very often they just show the end state, not the difference. E.g. if there are 2 prod already, and you will loose 1, then finally there will be 1 prod. And the tooltip will show 1 prod.
I also don’t recall ever seeing a tooltip with negative yields, like -1 prod.