FFMPEG fade out image overlay issue on windows 10
In zoompan, you have set d=125 so @ 25 fps, zoompan will create a 5-second stream.
Thus there are no frames after 5s for the fade to be applied to. The duration of the stream should be enough to cover the end of the fade transition. For st=5:d=1, total duration should be 5+1=6 or more.
Change to d=150.
P.S. In d=25*4:d=125 the first d=VALUE is overridden by the 2nd one, so it is useless.