I'd be very surprised if this were true. My iPhone 11 goes head-to-head with my mid-range mirrorless camera setup in most shooting conditions. Modern phone cameras are surprisingly good, really.
Really? I've done comparisons with my GR3 and my iPhone and even when browsing thumbnails it gets pretty obvious which is which quality wise. When I start looking at the photos on my desktop or iPad it becomes even more evident. It might be the kit lens your using or your taking pictures in bright sunlight only, which at that point the camera doesn't matter that much anymore.