This keeps happening, just reporting since it says so :)

[22:43:53] [Server thread/WARN] [APTweaks:EntityManager/]: Unknown entity name for entity ElectricArcEntity['entity.cofh_core.electric_arc'/3034162, l='ServerLevel[world]', x=1553.87, y=64.00, z=507.62] (entity.cofh_core.electric_arc) in minecraft:overworld. Please report this issue under https://github.com/MarkusBordihn/BOs-Adaptive-Performance-Tweaks/issues/!

Version 1.16.4, most recent cofh version.

Thanks a lot for the report. The warning message should be disappear with the next update.