What I have personally noticed in last few weeks

I have been running a faucet for last few months, and have noticed many Strange things in the last few weeks from coins going down at a rate of 30 people claiming and only 3 showing on analytics.

Bots usually just brute force CAPTCHAS and if your monetising from your CAPTCHAS your CPM will drop to basically nothing because of the high fail rate. If you look at impressions on solvemedia and see a big red band on the chart much greater than the green solve its a sure sign of bot activity. Also ad revenue becomes worthless.

I think we need to come up with a way to stop multiple failed CAPTCHA attempts. I have noticed that in my case the higher the bot activity the longer the sessions show in analytics