Living Bomb Reduced Duration bugged

Living Bomb's seed duration is 2.5s. With 20% quality it goes to 2s.
With Overabundance and fast foward (80% reduced duration) it should go to 0.4s but it goes 0.7s

I did some testing, appearently the calculation to this is being done 1 support gem after the other. it goes 50% reduced, then it goes 30% reduced fron the result of the before. Is it it how it was supposed to be?

To answere your question: Its not, the correct duration is 0.7 seconds.

Now to answere why, so in future you never have to ask such a question again:

In path of exile (and path of exile 2) there is a strong empathis on wording. A global, general rule, that you realy need to hammer in your brain is:

Less/more is multiplicative
Increased/reduced is additiv


overabundance gives 50% LESS skill effect duration
fast forward gives 30% LESS skill afect duration

These are multiplicative modifiers!

So 2 seconds base duration with overabundance giving 50% less resuslts in 1 second duration. Fast forward gives 30% less resuilting in 0,7 seconds duration.