In the iPhone 4/4s era, hardware SIM interposers (like the R-SIM or Gevey SIM) could temporarily bypass carrier locks. Some users installed these and then used 3uTools to flash custom carrier bundles. That method on modern iPhones (iPhone 6 and newer) and often leads to signal drops.
If you want, I can draft a short consumer-facing warning you can post where those claims appear or produce step-by-step tests to verify whether a claimed unlock is permanent for a specific device model and iOS version. carrier unlock iphone using 3utools exclusive