If you hover over the Audiograms Pro help icon on the right, (midway down in the Pro plan card) it says "Custom colors, background images, and remove the Descript logo. 30 min max size (vs. 2 minutes)"
But it seems like that only applies to the "Audiograms" feature, not the videos you export from the main product (?)
https://help.descript.com/hc/en-us/articles/360042638351-Aud...