Wow, there's so much going on here.
Was the red mark some strawberry from the cake Creepy was eating or something else..
Did Flora just cover up the red mark with a painted-on tongue or is the painting alive?
Is the painting after that strawberry cake, or after Flora?
Did it's pupils move in the last panel? Creepy seems concerned.
Edit: Actually the SFX in the last panel is ぺろ (pero) a Japanese onomatopoeia for licking sounds.
So the painting cleaned itself up of whatever that red was, like a real cat.