My point light sources leave a this trail effect that becomes very visible when the frame rate is lowered. I created them using a sphere mesh with an emissive material. I’ve tried turning off motion blur, messing around with Lumen properties, but to no avail.
small emissive material light sources are not well supported in lumen. they don’t fill the lumen scene to a point where they are stable. you should use analytical lights aka real light sources.
be aware that adding real lamps requires monitoring of light overlap and properly managed attenuation distances and light values.
5.4.2+ has an experimental/beta feature called manylights to assist with lots of lamps. it’s a raytracing feature tho.