This is a known issue with performant and it breaking other mods, the author does not care

i cant start my personal modpack idk whats the problem

The modpack you're using includes both BiggerReactors/Phosphophyllite, and the Performant mod (as mentioned in the issue). Performant breaks a lot of mods (IIRC due to it throttling the tick rate), including Phosphophyllite, and the author does not care. So an error check was added to check for Performant on launch. Either remove Performant, or enable the hidden config option to bypass this check (if you do this config bypass, then we, the developers, will provide no support for the mod; check the log file or issue #3 for instructions on how to do this).