Page disappears to the right in Safari?

Occasionally, when I'm filling out a form in Safari, the page suddenly slides to the right and disappears, and a previous page that was underneath it becomes visible. In the history I can see several instances of the site that I'm on (buzz sprout.com) but when I go back to those pages, the form is blank -- extremely frustrating. I saw someone post a question about this in 2020, but there was no solution at that time. Can someone help me out?