For reads across different VMs on the same CPU, theoretically TME-MK could mitigate the usefulness of the memory reads by having each VM access memory using a different memory encryption key, but I don't know of any hypervisors that implement this.

AMD has had SEV support in QEMU for a long time, which some cloud hosting providers use already, that would mitigate any such issue if it occurred on AMD EPYC processors.