I’ve just been past the “Derwent Overlook” laybys (the big ones just before you get to the Fairholmes visitor centre below the dam) and it appears that, if they were planning to introduce parking charges there, they’ve changed their mind. I can’t remember if they’d actually got round to installing pay-and-display machines, but there are none there now, and the new sign now seems to have the line about pay and display more effectively obliterated than it was. The PDNP website (https://www.peakdistrict.gov.uk/visiting/planning-your-visit/parking/parking-locations) also now clearly says that parking there is free. The same web page also now shows the Hooks Carr and Dennis Knoll laybys below Stanage as free, though the Hollin Bank (Plantation) carpark remains Pay and Display.
The road beyond Fairholmes up to Kings Tree at the top of the Derwent Valley is also now open again Mon-Fri (they seem to have finished the work they were doing on the inlet just above the Derwent dam over the past couple of months, and have re-landscaped the area where the crane was). Unsurprisingly after the recent rain, water is now cascading over the tops of both dams.