In my survival world i made a classic mob farm and covered the top with bottom slabs the farm wasnt working in the day after searching for why i found that spawning areas had high sky light levels. Optimize world which fixed the issue temporarily but after a few minutes spawning layers had skylight access again i optimized again and loaded the map without phospor issue resolved so i imagine its caused by this mod. Ill post screenshots later when i am at home.

Other mods Lithium,Sodium

Feel free to reopen if the issue still occurs with Phosphor 0.7.1 (after optimizing the world once).