I’ve double checked our game designer, and I apologize for the incomplete statement.
The overall energy gain is getting buffed in fit chests and dark rush (without spending premium currencies) but will only be noticeable if you can beat dark rush wave 25+ and levelled up all the powerups. We’ve been watching the analytic data really close for the past week and will make a call whether to adjust the step->energy ratio soon.
Please keep sharing your feedback with us and thank you for your patience on this!