How to test stationarity of Freatures?

Hello guys this is my first time using Nuemrai. I wonder how to test the stationarity of Features since there are only 5 values [0,0.25,0.5,0.75,1] for each features. I am not sure if the traditional way like ADF test works here. Thank you for your idea in advance!

One direction could be looking at changes per era in correlations of a feature with other features and the target.