Different Watts between ERG and Non ERG

Hi There, Im noticing that my efforts during a workout (ERG mode) are much harder than just normal riding for the same Watts (Non ERG mode)
So 200w in normal riding is much easier than in ERG mode, does anyone else have this issue or am i doing something wrong? or an incorrect setting? Thanks for any help

Are you riding the same cadence? If you spin faster in erg, it will get easier, if you spin slower it’ll be harder