Wrong BG Color, when site loads

Hello everyone! I ran into such a problem: I added a background color change to the site when scrolling certain sections. For some reason, when you first visit the site, the background turns yellow, as it should be on the penultimate section. However, if you scroll the site down even a little, then the problem disappears, even if you go back to the very top of the site. How to fix it?

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