i've been noticing if I target another champion and look at their items, there tends to be a number in the lower right hand corner of each item, what is this number? what does it represent?

not all items have it, at first I thought it was how much it's grown but some items that dont even grow like the boots also have these numbers some times

my other guess is that its how long the player has had the item, but im not sure, can someone explain what this number is?

its a bug

when you stack consumables the number appears, sometimes when an enemy sells the consumables in that slot and buys an item the number does not disappear