See faling tests: https://wpt.fyi/results/resource-timing/crossorigin-sandwich-no-TAO.sub.html?label=master&product=chrome%5Bexperimental%5D&product=edge&product=firefox%5Bexperimental%5D&product=safari%5Bexperimental%5D&aligned Also: https://github.com/w3c/resource-timing/issues/207
There might be some cross-origin security / privacy implication here.