This was a change in a recent beta release
In other words, if there's nothing happening on the screen, the fps will "drop" simply because it's not necessary to redraw the screen.
We've also made some changes to framerate handling to clear up some confusion. Firstly, the standard frames per second (FPS) measurement previously actually measured ticks per second, and so could still read 60 FPS even if nothing was being rendered, which happens when nothing is changing. We've changed it to now only measured rendered frames per second, so it will drop to 0 when nothing is being rendered. We've added back a separate ticks per second (TPS) measurement which reflects the old measurement. This all makes it clearer to identify the rate at which frames are drawn and ticks are processed, which are not always the same. We've also changed the 'Set min/max framerate' action to 'Set min/max delta-time' to more accurately reflect what it does, as using the term 'framerate' is a bit misleading there.
I'm just not sure why the other example doesn't show this drop since there's also nothing happening on screen...