As an ex farmer who would very familiar with Roundup; I found I don't know everything this spring.
Here is advice to others out there.
Make sure you have a gallon hand sprayer for Roundup, and another separate sprayer for broad leaf weeds.
Also make sure before you spray broad leaf weedkiller on your lawn; that you actually put broad leaf killer in the sprayer. Things don't turn out very well if you spray Roundup by mistake!
Especially when you are an ex farmer that (used to) makes fun of city people who who accidentally spray Roundup on their yards!
...funny you bring that up.
I learned that lesson 20 years ago the hard way. I actually have 3 separate sprayers painted different colors now. One for herbicides, one for roundup only and one for pesticides. It seems you can never really get ALL of the chemical out of a plastic tank so I just dedicate one for roundup and be done with it.