What is the purpose of tiny "bumps" on LED legs?
From here this is what the leadframe looks like.

This is what they look like when they are molded in small scale production:

After this, the parts are separated but the die is made so that it does not weaken the lead, which means it has to be a bit wider in that area. So the remaining nubs are artifacts of the production process, like ejector pin marks on a molding.