Fishfinders scare fish?

They do, but only if you have a banana on board.

Many years ago I had an older Chris Craft with a Raytheon commercial sonar unit. I never thought it would spook fish.
One day I was swimming away from the boat and I could hear a very loud clicking sound underwater. I forgot and had left the sonar on, after returning to the boat just before climbing onto swim step I put my hand close to the transducer and could feel the clicks and a dull pain in my hand bones from the energy coming from the sonar, After that I always turned it off if I was anchored and fishing.
Now if I am swimming around my boat with newer CHIRP there is not a high power signal like that old Raytheon unit.
Does the Garmin on my kayak spook fish???? I don't think so!