Suspected BUG - Flicker Strike without spending power charge.

https://www.youtube.com/watch?v=MTGlY2irUDU

The suspected BUG is shown in the video. [00:00-00:10]

For My build,
The maximum capacity of power charge is 5

In the video 00:00 - 00:10
I used the skill flicker strike.

However, the five power charge didn't spent.

And i was able to use the flicker strike with five charges again.

BUT....
In the normal situation, power charge should be spent.

Also,
In my observation,
Even i equips Perpetual charge.
The charges should become zero after the flicker strike is finished.

but the power charges just remained. which is shown in the video.

I hope this video could help. I love POE2 so much. Its a masterpiece.
BTW, It just a suspected bug. Please ignore me if i'm wrong.
Thank you.

You aren't losing charges because you killed the mobs before the charges got spent. Unless you don't have perpetual or %quality on the skill gem this is working as intended.