On 2020 and newer Toyotas the hands-free microphone and the front-right speaker route through the DCM, so pulling the fuse or unplugging the module breaks them. A bypass harness sits between the DCM connector and the factory harness, severs the cellular path, and is designed to preserve the mic and speaker functions that route through the module.
Most ordinary vehicle functions should remain intact, but every Toyota communication-dependent service stops working, which is the point. Depending on model, that may include SOS, remote services, emergency calling, Wi-Fi, vehicle health reports, stolen-vehicle functions, and any microphone routing that depends on the DCM. Verify fitment for your exact model and year before install, and treat this as an advanced modification for vehicles you own and understand.
This is the fallback when a pre-2020 clean car is not an option. Disconnecting the cellular and GPS antenna leads at the module achieves the same result for people comfortable with trim removal. Toyota’s current privacy notice also says owners can opt out of Connected Services or request deactivation of data transmission; that is a legitimate lower-assurance tier, but it is not the same as removing or bypassing the radio path.