Hi there. i used to work for one of the swap gas companies.
there are differences in mixtures of LPG depending on where the supply comes from, and some cheaper LPG blends containing a mix of gases that fall under the classification of lpg, with the main ingredient being propane gas. this can cause the flame to burn more yellow and less efficiently than pure propane.
my experience was that no company will talk about what they blend with the propane, or how much. what you may never see is the blackening of the inside of the jets due to this poor burn mixture, which will ultimately cause your equipment issues over the long term and restrict flow.
so if you do experience issues with a particular brand of lpg, try another brand and you may need to stick with it. by the way, swap n go is a brand name which is used generically - which 'swap' brand caused the flame issue?