Season 6 of Schitt's Creek was a love letter to the fans, with callbacks to the other seasons littered throughout every episode.
Dan has been very candid about how David's sweaters tell stories about his character over the six seasons of the show. They made deliberate choices about his wardrobe, including purposely giving him a softer aesthetic as the series progressed and thoughtfully working in colour. When David wears colour it is saying something. It's important.
In the Open Mic episode, a significant moment for David and Patrick, David wears a DaVinci sweater with flames on it representing a love that was being ignited.
In Start Spreading the News, another turning point for David and Patrick, David wears an Off-White sweatshirt that features open hands with a flame inside, symbolizing openness, honesty, and again that flame of love.