@csehz Hi Zsolt, You’re quite welcome 😊
I experienced such artifacts when a light source is too close to, or shining directly into, a very reflective surface. Had this mostly with area lights (those area lights do not yet understand how awesome Eevee is, so they’re teasing us a bit 😛).
You could try to move away / rotate some of the lights, or change it to another type of lamp to see if that helps. Sometimes it also helps to change a material that a light goes through, or bounces against near a reflective surface, to a more rough surface (so less reflective).
I don’t know from which light source it’s coming in your scene, but if it’s the lights next to the mirror, and above suggestions don’t work, then you might have to move the lights to another position, turn them off or even delete one or both…
If it’s coming from the outside light source it’s probably from a round area light or spot light? If so I recommend changing it to a sun lamp. Had the least problems with sun lamps those seem to be well integrated.
Also a question to be sure, are you using a reflection plane for the mirror? That also helps to get rid of weird reflections.
Hope this helps!
