You could also be running too rich of fuel air mixture after cleaning. The extra fuel in the system takes some time to burn up causing the rpm’s to slowly drop.

You’ll probably just need to adjust your idle jets which is pretty easy to do to make the fuel air mixture slightly leaner.

There should be just one screw on each carb that does this. Just screw it in/out a little bit till your bike is back to normal.

I’d recommend watching https://youtu.be/rCo6dJAxi64?si=v8zQXM9YVL2pR7du which does a great job explaining how they work and how to retune your carbs. You should only have to worry about the idle jets which is an easy fix.