I’ve noted similar effects one of my sites, ppemail.net 6.
Some opening text/images on my landing page are set to 0% initially and are to appear upon scroll. However, they flash upon initial load, after refresh, and more pronounced after emptying cache. It happened regularly on Safari browser v 14 and continues on 15.
Seems Sparkle program loads them then activates opacity. Perhaps opacity needs to be set first before loading, but I suspect it is more complicated as @duncan noted. :wink:
Thanks for the work on this.
Problematic effect
Desired effect