Count me as one more person very interested in this!
Luckily, the bug is already being tracked here: https://bugs.webkit.org/show_bug.cgi?id=238497
In the mean time, a (very annoying) workaround may look like this:
el.style.overflow = 'auto';
window.requestAnimationFrame(() => el.scrollTo({ left: 100, behavior: 'smooth' }));
setTimeout(() => (el.style.overflow = 'hidden'), 1000);
There are obviously more robust ways to accomplish this (e.g. throttled onScroll watcher to re-apply the hidden style), but this gets the job done at least.
Alternatively, if it works with your UI, you can simply apply a pointer-events: none on the scrolling element to prevent the user from interacting with it.
Topic:
Safari & Web
SubTopic:
General
Tags: