Can you be a bit more detailed? For example, are you switching tabs? Switching apps? Or perhaps staying on the same page and just scrolling through things?
Just as I like to be careful on assumptions, you’re seeing the while search term, right? Sometimes when we click on the search bar, it highlights text. Then when we continue typing, it overwrites it. While I’m assuming you’re mindful of this and it isn’t what’s happening, I have learned it’s good to confirm.
I’m thinking you may be experiencing issue as related to Address bar search Bug
If so, can you also confirm if you have Show autocomplete suggestions in the address bar disabled in your settings? And if so, whether enabling fixes it for you?