I noticed that there are currently no thunderstorms naturally occuring in 1.16.2 Pre-release 1.
I tested in an existing world and a world newly created in the Pre-Release. The respected gamerule doWeatherCycle is set to true. From my understanding, a thunderstorm should occure at least once per 150 minutes, which for me is not the case. I did not use a bed to skip the night.