Ok apparently he drowned in the hot tub, but no drugs or other substances were found. Guess we'll find out more over time. I think its likely something in him gave up, one of his organs or maybe an embolism.
Jason David Frank- former power ranger and MMA fighter has died at the age of 49
https://www.joblo.com/r-i-p-jason-david-frank-green-power-ranger-dead-at-49/