“Floof-brained” is a playful term that combines “floof” a slang term for something soft and fluffy, often used to describe animals with fluffy fur and “brained” to describe a state where someone’s mind feels light and empty, like fluff. This can happen when an intelligent person numbs their brain with substances, leading to a feeling of mental emptiness. Brain goes into "power saving mode" and the mind feels light, quiet and worry free.
It’s a humorous way to describe someone who is temporarily not thinking clearly or is mentally foggy. Does that make sense?
"I can't make any decisions right now, I'm too floof-brained"