@skip:webkit. Safari is the browser; WebKit is the engine underneath it, and that is what actually gets driven. There is no separate Safari target, so the engine name is the only honest thing to write.
gherkin
@ui @regression @skip:webkit
Scenario: Apple Pay is offered at checkout
If it is really the mobile Safari viewport you cannot support, @skip:mobile-safari is a distinct target and skipping one does not skip the other.
Two things not to do instead. Do not use bare @skip — that removes the scenario from every browser, and lint passes it through without comment because it is a runner control tag. And do not branch on the browser inside a step; the point of the tag is that the exclusion shows up in the report as a skip against a named engine, so the gap is visible rather than hidden in code.