I was browsing through the tools* folders to understand what each of the scripts did and the update_screenshots.py script failed with with a TypeError, for full error and traceback, see the attached log file. In short, the script crashed when trying to set the preference window to show the experimental preferences, since the experimental preferences can't be shown by default.

The solution is to turn on Developer Extras under Interface, in the Python API this is done with context.preferences.view.show_developer_ui = True.

I didn't know if it'd be okay to show the Experimental "tab" (are they called tabs when stacked vertically?) in the other screenshots, so I added an if-statement before and after the tab change to check if we are taking a screenshot of the Experimental tab and if so turn it on and off temporarily.

This change makes the Experimental tab visible in the screenshot (only this screenshot, not for the other tabs). It could be changed to hide the Experimental tab even when taking a screenshot of that tab by moving the second if-statement before the yeild, but I thought that looked a bit confusing.

I also noticed that there doesn't exist a screenshot of the Experimental tab and that it isn't referenced anywhere in the manual, though there exist an entry for it under Editor > Preferences > Experimental.

Another thing I noticed was that this script hasn't been run for quite some time, the current screenshot of the splash image is from v. 2.80 beta.