Greetings,varinia48.
Welcome to the Apple Support Communities. We can certainly understand why you’d want to resolve the issue with your iPhone ringing while on silent.
To start, can you confirm if the calls ringing through are from Emergency Contacts? If so, this is an expected behavior. You can learn more about that, here: Use Emergency SOS on your iPhone
If the calls are not coming from Emergency Contacts, toggle the Ring/Silent switch and Restart your iPhone.
After restarting, navigate to Settings > Sounds & Haptics and toggle on ‘Vibrate on Silent”. Then, change your ringtone to a default ringtone: Use tones and ringtones with your iPhone, iPad, or iPod touch
Disable the Silent switch, place the device in silent and test to see if the issue continues. If so, Contact Apple Support.
All the best.