I've noticed that happen when browsing from outside the US on many sites recently, including Ercot. Extremely annoying. It's companies paying for Imperva's web firewall ("Cloud Application Security") that just blocks IPs based on country for no reason.

https://www.imperva.com/why-am-i-seeing-this-page/

Real-Time System Conditions

Last Updated: Feb 20, 2021 16:51:26 Frequency Current Frequency 60.007

Instantaneous Time Error -24.595

Consecutive BAAL Clock-Minute Exceedances (min) 0

Real-Time Data Actual System Demand 33772

Total System Capacity (not including Ancillary Services) 60667

Total Wind Output 8646

Total PVGR Output 323

Current System Inertia 223646

DC Tie Flows DC_E (East) -299 DC_L (Laredo VFT) 0 DC_N (North) -219 DC_R (Railroad) 0 DC_S (Eagle Pass) 0

Here's screenshot of 15 min spot price page https://ibb.co/YTzsqdj