I was raking my brain since the update of ios 26 about this issue and today i went thru this thread and someone suggested cross fade transitions. So i reduced motion and disabled cross fade transitions or toggled it off. And it worked! It finally worked!!!

Just go to accessibility > motion > prefer crossfade transitions to off and turn reduce motion “on”

i am not coding so coders plz excuse my intrusion but for endusers like me this is working for me. No more sticky elements scrolling up to middle of the screen and annoying me.

Apologies if this reply is in the wrong place but it had to be put out there somewhere for someone facing the same issues with safari like i am.