Respect probably got charged twice - lost 100 energy
I started with 133 energy and did a few battles. Then I used the free respec.
After activating it, the respec window got stuck. I refreshed the page, but all my skills were still allocated. I tried activating the respec again, which generated a system error. However, after refreshing once more, my skills had been reset successfully.
I continued playing and did a few more battles. Later, I noticed that my energy had dropped to around 25 (I don't remember the exact amount, but it was somewhere between 25 and 29).
It looks like the respec may have been processed twice, consuming an extra 100 energy.