SSL Pinning in android

Hi all,
I’m pretty new to ionic/capacitor
I have to invoke an https end point on another server.
After a long search I found this great example GitHub - ashenwgt/ionic-capacitor-ssl-pinning: Sample Ionic + Angular + Capacitor App to test SSL Pinning

I tried it a month ago and it works like a charm.
Today, tested again and the app keep telling me “Trust anchor path not found”.
I didnt modify anything in the code, I downloaded from github again and I have the same result.

Why is so difficult perform an SSL Pinning?
Someone can help me with this example and tell me what suddenly stops working?

Thank you so much