Hello. A fellow member in the community pointed this odd glitch out and I am reporting it. In /shop Rotten Flesh appears in two different places: Food and Mob Drops. As shown in screenshots below, Rotten Flesh is Buy Price $6, Sell Price $1 in Food category and in the Mob Drops category it is Bought for $6 and sold for $3. $2 might not seem like much, but it is very big in huge amounts. Thank you.
Credits to ActaeaMadi for finding this glitch.