wrong contour lines in 500hpa geopotential
kindly note that the 5000hpa geopotential height are wrong in shape
attached images are included for the same period of time to be aware of this..
With the Windy map you show Geopotential heights at sea level ! It is not possible to have the 500hPa Geopotential heights with Rain layer. You can with Temperature, Wind, Humidity or Dew point layers only. At this level, Windy shows 4 digits because they are expressed in meters, not 3 as your screenshot shows.
In these examples both at 12:00 UTC the Isolines are similar but showing a deformation due to 2 different projections.
what does those 3digit numbers express?
gph in meters at 1000 hpa ?
I don’t know precisely, probably less than 1013 hPa. Try to set Altitude at surface, gph are between 0m and 600m, and sometime negative in Lows. So 1000hPa seems possible.
IMO in the broad sense, it is a bug.