why is BF% a issue when starting a first cycle ??

i haven't started because im listening and reading !!

i messed up when i was young and dont want a repeat of that !

im 39 250lbs 6'4''
i dont know my BF% i guessed around 20%
i cans see a abb outlines and i have seperation between muscel groups
waist is 38 chest 50

how can having a high % of BF affect a cycle and does it bring greater risk of sides like gyno ??