The bigger part, the royalty fee, was expressed as a percentage:

The rate increase was mandated by Congress under the 2022 Inflation Reduction Act, which directed the Interior Department to raise the royalty fee from 12.5 percent, set in 1920, to 16.67 percent. Congress also stipulated that the minimum bid at auctions for drilling leases should be raised from $2 per acre to $10 per acre.

I’ll note that even the higher rate is lower than what most countries end up charging.