New penalty by google very complex to grasp

Today i found this penalty for one of my client site and you can't imagine how this penalty got and what is this penalty. I have seen this penalty in my career first time and never heard from any seo expert or professional.

I have a website since 10 years and it was gone in penalty for 2 years because of duplicate title tags which i was not aware. So after 2 years I solved around 500 duplicate title and content pages and it again started ranking at 1st page of google. More than 200 keywords are ranking at first page which are competitive. But today I found that my all keywords are again fall down which i have optimized since 1 year. But rest of the keywords which are stable at when 2 year pentaly is laid. so only those keywords which i have optimized for 1 year ( i have done too much off page optimization of these 200 keywords).

I have not done any bad technique on page. though I have done too much of off page with different keywords for same url. I want to know what is this penalty. Also when i have removed all duplicates then google increase my traffic from 200 to 1000 per day.

After doing much reserch i found some possible cause

1) My site is in moderation by google

2) I may have got penalty for overoptimization

3) Beacuase of high traffic in short time ?