Hey RCNCCLT,
I understand you're having trouble with phone calls from unknown numbers being silenced, even with the Silence Unknown Callers feature toggled off.
Are you using Dual SIM with your device? If so, if one line is enabled and the other isn't that is receiving the call, it's normal behavior for that call to go to voicemail. Learn more here: Using Dual SIM with an eSIM - Apple Support
If you're not using Dual SIM but still having trouble, make sure that Do Not Disturb is off in Settings > Do Not Disturb. Also open the Clock app > Bedtime > Options in the upper-left corner and make sure Do Not Disturb during bedtime is off, if the calls you receive are during these times.
Also check your blocked list for any possible blocked numbers by going to Settings > Phone > Blocked.
Keep us updated. Cheers!