As of https://github.com/zloirock/core-js/commit/8699b9a3024c1703d7b158ad3236288b38633af6 and https://github.com/zloirock/core-js/issues/656 in WebKit 2.28.4
new URL('http://x', undefined)
throws a TypeError, but in Firefox 89, Chromium 85, nodejs 14.9 it does not throw an error.
I cannot reproduce this is Safari 14. Maybe already fixed?
In my Safari Version 14.0 (15610.1.28.1.9) `new URL('http://x', undefined)` does throw.
But in current Safari Technology Preview (Release 113, 15610.2.3.1), it doesn’t throw.