How are you meant to clean your weapon? I got a warning to say it was dirty but I don’t know how to clean it to make it better?
You need to go to a proper work bench. You won’t be able to clean it using your backpack. You really should since all it takes is chemicals but either way go to a proper work bench at a settlement or something.
Open the work bench, go to weapons and the first item on the list should be the clean option. Hold the button to clean the weapon and it will begin to recharge the cleanliness level of that weapon. Once it’s full the weapons will be good as new. You will visibily see it get cleaner as you hold the button down.