The most common way to fix this problem seems to be to leave the figure in direct sunlight. This can be risky, as you don’t want to fade the card or help yellow the bubble, so stay with your figure while doing this. First, cover the picture part of the card with thick paper, cardboard, etc… This is to cover all the parts of the card back that can fade. Next, lay the figure in the sunlight and let it hit the figure under the bubble. For the fuzz to go away it can take as little as 10 minutes, and as much as 45 min. to an hour. You will want to stay with the figure while doing this, to lower the risk of damage.
The theory behind this is that the “fuzz” is a mold, and the sunlight will kill the mold.