For now, QEMU supports only 3 CPU architectures (AMD, IBM POWER and IBM S390x), as properly hinted in comment So for Intel and other(?) architectures, support doesn't exist yet - one can find it in QEMU documentation about Confidential Guest Support

Hence, in order to "fix" this, someone has to write new code for QEMU, and that also depends whether Intel and others have documentation and allow it to be open source.

For Intel, it is most likely TDX extension technology.