It's unethical because you can't safely perform muscle biopsies at home, thus it is a violation of the duty of care, and culturing stratified squamous epithelium and calling it meat(and steak no less) is lying without any benefit to others, which is a fundamental ethical violation.
I think you would get the copy of a copy problem. DNA in cells degrade overtime. I think with lab grown meat this is much worse than normal human aging.