So how does the math of rocket boots work exactly?

I thought I had a handle on it

Instead of 146 seconds it's down to about 40 seconds now, well it used to be 146 seconds on live it's 92 seconds now (5560 / 60 frames).
no companion is around 31~32 seconds of flight time also

Did you turn off +ncharge regen while rocket boots were active or half the -%cost too by mistake and didnt mention it in any patch notes?

or perhaps changing the half cost to reflect flight time than the modules ncharge cost?