Webpages created in Express using a split-screen layout often fail to scroll

On mobile devices, webpages created in Express using a split-screen layout often fail to scroll.

When scrolling down the page, the view appears to “lock” or stop responding for a painful amount of scrolling, giving the impression that no further content exists.

After repeated or prolonged scrolling attempts, the page will eventually continue. The issue occurs even with minimal content (plain text and a single image) and seems worse when there is a lot of content in the aside panel. This hasn't been a problem in the past and appears to be a problem on a range of Android devices (Pixel 8a & Pixel 10, running Chrome).