A group of chatters who gather online in a cyber chat room known as “talk chat,” are being used by a top secret government agency as a select group of control test subjects for large scale social experiments without their knowledge.

I agree with Richiev that you've set up the situation but we do not know "So what?"

Good writing. Lx

When a socially awkward computer genius uncovers that his favourite social media app is used as experiment for mind control, he must use both life and cyber skills to expose the conspiracy by a special branch of the government.

As written, I am not seeing any danger here; or any action.

Some people in a chat room are being experimented on
They don't know it

That doesn't mean there is no danger, I'm just not seeing it in the logline.

This logline needs stakes! Something people reading it can relate to. What is the danger they are facing?

This logline also needs a lead character. (Is the lead character one of the "Chatters" or the one doing the experiment?)

Finally it needs to be condensed a little.

Hope that helped, good luck with this!