There is zero evidence at all for any antibody-dependent enhancement with the COVID vaccines so far. The mRNA vaccines also induce the cell-mediated immunity,

There is zero evidence at all for any antibody-dependent enhancement with the COVID vaccines so far. The mRNA vaccines also induce the cell-mediated immunity, unlike e.g. subunit vaccines that only consists of a protein. The cell-based response is fundamentally different and not based on the 3D structure of the virus protein like the antibody response. So mutation that would evade the antibody response would not automatically evade the cell-based response as well. The spike protein is also the most important protein of the virus. And antibodies are mostly useful against surface components of the virus, not so much against stuff that's on the inside. The spike protein performs a critical function, to evade the antibody response it has to do both, change enough to be unrecognizable while still being able to infect cells with a similar efficiency. That's not an easy thing to do.