When you’re using it, or when it’s stored? Do you de-pressurise it when it’s not in use?
Well….
First question, are they soft green weeds or brown woody weeds?
For the soft green stems - annual weeds - if possible just pull them up. I’m nit convinced that there is anything in that photo that needs weedkillering. Only if they have deep roots, like dandelions, or woody perennial weeds like brambles. might weedkiller be appropriate.
For woody weeds, the glyphosate needs to be absorbed by green living leaves. You might consider partially chopping them, but you need to leave enough green growth that you can effectively spray.