Hi,
As of Firefox 88, the Take a screenshot option will no longer be available from the Page Actions (three dots) menu. However, you can right-click on an empty part of the page to find the same feature.
Alternatively, you can use the keyboard shortcut (Ctrl+Shift+S) for Windows and Linux or (command+shift+S) for Mac to take a screenshot.
Read more in the following article: Take screenshots in Firefox.
