This has been happening across nearly every weather source I've been using. My hypothesis is either:
* Climate change is causing problems with forecasting models
* Forecasting models changed, which has introduce unexpected edge cases
* Climate change is causing problems with forecasting models
* Forecasting models changed, which has introduce unexpected edge cases
https://www.sciencedaily.com/releases/2020/07/200717101026.h...
While this is confirmation bias, this reflects almost identically with the timeframe in which the forecasts became significantly worse in my area.
I'm not sure this happens on the time scale of 'app got acquired', though. It's absolutely going to increase year by year, and if you'd got used to how it was three years ago and didn't notice some of the outlier events, you might be shocked at the new normal.
Climate change absolutely will cause problems with any conceivable forecasting model because you can't encapsulate chaos, only map its expected potential outcomes: and the nasty truth is that energy is fed into the system, those potential outcomes blow up exponentially. Not even slightly linear. So that's what we're seeing.
So I'd not be surprised if they somehow switched their data source to be not as granular as it once was.