Ok, so I have started over. Deleted all helpers, and all automations.
I am testing two separate Govee lights. Light 1 controlled from Keypad button B and Light 2 controlled from the same Keypad (button C).
When I set up the Linked Entity, I select the Govee Light 1 and have two options to link to it. A switch and a sensor. Neither work. So I created a scene in the eisy and put only Button B in it. That seems to work.
However, I did the same exact process with Govee Light 2 and Button C, and it constantly turns on and off about every second. It will work fine the first couple times I press the Keypad button, but then goes back to constantly alternating states. This is very repeatable.
I'm at a loss. I am sure it is caused by something I am doing, but I have checked the set up in the eisy and in the HA automations, and they appear to be set up exactly the same. One seems to be working, the other doesn't.