The cap was raised to $9k to try and incentivize generation because the forward reserve margin was dwindling. ERCOT was the only electric market in the US that was actually growing and old thermal plants were retiring because they couldn’t economically compete with new renewables. Bill Hogan @ Harvard was commissioned to help solve this problem and his team created a new scarcity pricing mechanism along with higher price caps based on the value of lost load. These caps were set by the PUCT and ERCOT had no say in them.
Why are you so focused on caps and not on learning the difference between gas and power markets? You keep trying to simplify very complex systems and issues with a half baked understanding of some basic talking points and minimal understanding of how the markets actually operate.
This is true of any ISO in the country during extreme conditions and you wouldn’t want it to not be.