for those that use barrels to connect the line to the leader those bumps are also very small bass or hickories hitting the barrel.
I have seen it 15 feet in front of me.
seems to help to use the smallest barrel possible.
I use the tiny but,strong tsunamis the type that look like a sleeve with rounded ends.
at times they still hit it but,much less than with a normal sized barrel.
also the gators will hit the barrel too resulting in a cutoff,,have seen that too where the leader is cut 2 inches below the barrel.
even so if you don't use a barrel and connect with a knot they can see that too and will hit that.
it's amazing what a fish can see in the dark.