Coralline algea going away

[Psyire]

My guess would be that it's your lighting change.

Coralline is a deep water algae so it typically likes less light and you just went alittle brighter, so it's probably just going through an adjustment phase. I'm sure it'll come back but probably grow in different areas. Coralline adjustment peroids can take several months I believe, I wouldn't worry to much about it.