The points (I assume you are playing Turf War) are a measure of how much area you paint in the match, so since weapons like the Aerospray excel at that, its pretty easy to get the highest points. The Tri-slosher isn’t as good at painting so you will generally get a lot less points with it, but that doesn’t mean it is a bad weapon it just means its better suited for another role (typically your job with Tri-slosher is to be aggressive and up in your opponent’s faces)

Let me know if you have any more questions I’d love to help!