You should see the soupy poop from my flock after they gorge on chard and lettuce and squash. I also feed fermented feed, and it's rare to see firm poop. I also have four very old hens, and they have very soupy poop. Recently deceased was a hen who never once in her life had anything but soupy poop. She was eight years old when she became sick for the first time in her life.
Hot days mean lots of water consumed, and that means soupy poop. Are you beginning to get the idea here? There are many ways that healthy poop can be soupy.