I filed Feedback Assistant report FB24424949 for this issue. On macOS 26.6.2 (25G83) with Xcode 26.6 (17F112), Apple-signed simctl removed iOS 18.4 (22E238) and iOS 18.5 (22F77), but both re-registered from their SIP-protected MobileAssets after a normal restart and the CoreSimulator DYLD cache rebuilt. No manual filesystem deletion or SIP change was used. Posting the feedback number as requested by Apple DTS so this reproduction can be associated with the existing reports.