Non Inverting Summing Amplifier - Ripple Gain
The ripple is multiplied because the gain of your amplifier is 2.
The voltage in the "+" pin of the Opamp sees the green trace. If in that pin you see a DC of 1.65 and a ripple of (just guessing) 50mVpp, then at the output will get a 3.3v + a 100mVpp ripple.

The gain works for both signals, AC ripple, and DC.