iPhone automatically blocking callers

For a while now, my iPhone has been automatically blocking callers without my knowledge. This has caused me to miss important calls. For example, I was wondering why a local PC repair shop was not returning my calls regarding a laptop I sent in for repair. After further investigation, I found the repair shop's number under Blocked Contacts and several voicemails from them under Deleted Messages. I am 100% certain I did not block that number, especially considering that I was expecting a call from them. While I do have the Silence Unknown Callers option turned on, my understanding is this feature is not supposed to actually block such callers. However, I *have* manually blocked a lot of spam callers in recent years. For the record, I am using an iPhone 13 Pro Max with iOS version 17.5.1 currently installed. I get service from Verizon Wireless. They do offer a service called Verizon Call Filter that automatically blocks spam calls, but that requires a separate app, which I do not have installed. I’m curious if iOS use the Blocked Contacts list to train its spam detection system. Either way, how can I disable this "feature" and allow calls to come in without being blocked?