This is a very common issue with fixed domes with IR embedded.
You have comments and solutions on HIK web.
The problem comes from the black foam who don't apply correctly against the translucid plastic, so what you see is the reflection of the IR leds who reach the angles of the lens.
Dust and greased covers (fingers) also produces this result.
Check these 2 points and be sure the cover was cleaned correctly
There is also a post where you can see how to solve part of the problem.