I often use the keyboard for navigation instead of the mouse. Sometimes I even turn the oversized touchpad off altogether. Since launching the page previews feature, I noticed that the following happens:
- A link is focused/hovered in some way (e.g. by ctrl+f'ing on the page, tabbing to it, clicking by mouse, whatever)
- I immediately navigate away by hitting enter or clicking
- I later (sometimes seconds, sometimes hours) return to the page with backspace or with alt+left
- The page preview now opens, covering other text (making the following sentences unreadable).
When I hit escape, it doesn't close. When I tab to the next element, it opens that page preview instead. It seems one can only use the mouse to defocus the element.
I do not want to disable the previews altogether. They're not bad: it's just that there is no way of dismissing them when they erroneously show up (I just came from that page, I don't need the preview now...).
 It's not actually ctrl+f, but behaves very similar. I use the "Search for text when you start typing" feature in Firefox, as demonstrated here: https://www.reddit.com/r/RSI/comments/744dlq/if_you_work_a_lot_on_computers_avoid_the/