During the disaster the new head of the EPA forced Texas to set the price at an astronomical rate in order to run the coal and other plants at 100 percent. The EPA caused Texas huge financial pain that we are still paying for that $9,000 / MWh event.
$9000 per megawatt is the legislated by Republicans in Texas for the last 20+ years maximum rate ERCOT can ALLOW to be charged the market wanted to charge more at the time. The EPA thing was separate it only has to do with turbine derating to avoid NOx and PM2.5 emissions the EPA doesn’t set price only ERCOT does. The EPA said that plants who where already paying the legislature max rate could run flat out and break their EPA caps but plants not subject to the emergency rate could not those were all out of ERCOT area as importers since the whole of ERCOT was at the cap rate due to massive natural gas shortages for 90 hours.
here is the actual data, report and after action review it has all the hard numbers.
https://publications.anl.gov/anlpubs/2021/07/169454.pdf