I had something similar with white feathers for months, and what was that when I saw them, I could also feel my twin noticing them too. Like there’d be this little pulse in my chest right when the sign appeared. Started paying attention and it happened every single time.
With your yellow butterflies, since yellow is their favorite color, have you noticed any sensation when they show up? Because I’ve read that sometimes when a sign appears to you, your twin saw it themselves and was so affected that the mental picture traveled through the soul bond. The butterfly might be appearing in both your realities. Yellow is connected to the solar plexus chakra which governs self-esteem and personal power. For TFs, yellow butterflies during separation often signal spiritual growth happening.
Our signs tend to be personalized. Like, my feathers are always white because that’s connected to us specifically. Yours being yellow feels like their signature on the message. Three circling you during coffee though… that wasn’t subtle. Pay attention to what you were thinking about right before they appeared.