The Fedora iot-bootable-container built by osbuild-composer is not compatible with newer versions of bootc-image-builder.

bootc-image-builder sets root filesystem options that assume the base container image uses composefs (see https://github.com/osbuild/bootc-image-builder/commit/c609003ddd7a4116354692994f818f83afb59f7c) which is not true for the image built by osbuild-composer.

As the commit message says, one solution is to inspect the image and set the fstab options accordingly in bootc-image-builder. Alternatively, we can enable composefs for the iot-bootable-container but that might be more work. Long term we certainly support composefs.