Based on the graph below, we can see that fees paid on Polygon seems to be closely correlated to that of Ethereum. On further analysis, we can see from June to Aug, the rate of fees paid on Polygon is generally higher than ethereum. This relationship however changes on end Aug when the rate of Ethereum fees paid became higher than Polygon.

Note: As ethereum fees are significantly higher than polygon, the two graphs below is not drawn to scale on Y-axis for easier comparison.

The change in the rate of fees paid on Ethereum over taking Polygon is likely due to recent high gas fees on Ethereum. Interestingly, Polygon fees rate did not spike as much and when it did on each spike, it quickly goes back down.