Thunderstorms happened more than usual, at least once per in-game day.

Usually, thunderstorms happen very infrequently, but in some of my worlds it has been repeatedly happening again and again no matter how many times I use '/weather clear'. It is also worth noting that not once did I see a regular rainstorm happen.

It seems that this happens when I update a world to the snapshot 20w46a, as it did not happen immediately when I created a new world. No other steps were taken, I simply updated the world to the new snapshot and suddenly thunderstorms began happening frequently.