How can I fix the visual borders bug for Phaser 3 Particles?

Question

I use the Particle Emitter in Phaser 3 to make shooting stars in my background. This technically works great, but there is still a problem with the particles itself. Every particle has visual borders, even though the images don't have any borders. I can't use the particles that way, it looks like someone didn't cut the right. The particles are from the phaser github page. I use the blue.png, red.png and yellow.png. I didn't edit them. My particles are in an atlas. I'm viewing it in Chrome on windows and I'm using Phaser v3.55.2 (WebGL | Web Audio).

You can see the borders clearly in this image.

Here's my particle emitter:

this.emitter = this.particles.createEmitter({
        frame: 'particles/' + color + '.png',
        x: { start: this.endpoint + 700, end: this.endpoint, steps: 100 },
        y: { start: yStartpoint, end: yStartpoint + 300, steps: 100 },
        lifespan: 1000,
        speed: { min: 200, max: 400 },
        angle: 330,
        gravityY: 300,
        scale: { start: 0.2, end: 0 },
        quantity: 1,
        blendMode: 'ADD'
    })

The star- and endpoint are determined elsewhere and I doubt it has to do with the bug. Can someone tell me why this happens and what I can do to fix it?

Also another question: The particle emitters move faster when I have higher quantity. Maybe I'm not understanding what quantity means here, but shouldn't quantity be the amount of the particles?