Hi!
Because the section in the demo version and on-site was different, they had slightly different styles, namely in ScrollTrigger: start, end, and in styles - only height, indentation, and content, of course. I didn’t think much of it because I thought it wouldn’t affect on the scrollbar, but I was wrong...
I have priority to solve the problem on the site, codepen is necessary only for its presentation. You don’t mind if I print an exact copy of the horizontal section from the site to codepen, including its content? Styles will be more, respectively, lines of code too. I'll separate unnecessary styles to be more convenient, thanks in advance!