This number is always "NaN", the njk formatting hides such numbers so you see nothing.

AFAIS the used property precipitation_probability does not exist (anymore?) at least in the forecast (I did not check current and hourly).

Instead of precipitation_probability I found precipitation_hours so in openmeteo.js we could replace

			currentWeather.precipitationProbability = parseFloat(weather.precipitation_probability);

with

			currentWeather.precipitationProbability = parseFloat(weather.precipitation_hours * 100 / 24);

(I found numbers between 0 and 24 in precipitation_hours).