How to minimize unwanted effects of emissive materials?

Some emissive materials do strange things in the scene.
Especially when the emissive surface is narrow and elongated.
It seems to occur when viewed from the edge (more o less).

Basically it looks like it splits into pieces and moves around.
However, I didn’t program it to do that. I just wanted it to emit static colored light.

In this video you can see perfectly what happens.

The level looks like a discotheque.

Is there anything I can do to eradicate or minimize the side effect?

Thank you so much!!