We've been there.
It's impossible to stop fraudulent traffic when you don't change the way the site operates.

We were criticized when we changed the hourly roll to a daily roll but that's what saved our faucets.

If you want to overcome this fraudulent activity (and don't end up like freedoge.co.in had to shut down) you need to start changing your business model. First of all paying 3 sats at minimum roll is a pure suicide and doing it on a hourly basis is a disaster waiting to happen.

Change your business model first, then worry about how to stop the remaining fraudulent activity. The change itself will deter fraudsters from draining your Bitcoin reserves.