Request for identification of issue

[Cindar]

Hi all, I have come back from Christmas and my Red Sea Nano tank has a bit of an algae issue,…. Just wondering if anyone can ID it.

My parameters are all ok.

TDS:0
Salinity: 34.6ppm
Ammonia: 0
Nitrite: 0
Nitrate: 4ppm
PH: 8.1
Phosphate:0.03ppm
Temp: 25.5 degrees