If you are worried about strangers viewing your photos, Facebook offers a "Profile Picture Guard." When enabled:
On certain devices, it prevents others from taking a screenshot of your profile picture. private facebook profile picture viewer
Sometimes, a profile picture is indexed by Google before the user changes their privacy settings. You can try right-clicking the thumbnail and selecting "Search Image with Google." If you are worried about strangers viewing your
When a user sets their profile or photos to "Private" or "Friends Only," Facebook’s servers check the relationship between the requester and the owner before serving the image. these can track your browsing history
Some "viewers" are offered as browser extensions. Once installed, these can track your browsing history, steal cookies, or inject unwanted ads into every page you visit. Why Facebook Privacy is So Hard to Crack