Minor Fireworks Glitch

Hii,

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 continuously. I am not sure what the case may be.