Having an issue with fireworks.

I was not sure if anyone was able to see my past post, as it was already closed without further comment adding my gif to it.

I built a snow globe on a Minecraft server the other day. Fireworks shoot out of a dispenser in the middle of it. The dome was made out of regular glass, but I changed it to white stained glass (as shown in the GIF attached). When changing the glass, I noticed that when a firework is spawned, it seems as if there's a big shadow over the snow globe or some blocks appear to be appearing/disappearing. I am not sure what the case may be.

Gif: https://i.imgflip.com/18oowp.gif