How old is the battery? Often poor connections or even venting or small leak will cause quick corrosion.
Try coating the terminal with Vaseline, or use a battery terminal protector spay & see if that helps.
Side post are not the best, as you try to keep em tight, they can strip.
Was not long of owning the PK Ave before I got a sealed AGM battery and moved to a top post solution.
AGM batteries are fully sealed & do not vent= no corrosion.