There are several Kveik strains... which one did you use? May we know the full recipe, fermentation temperature and schedule, etc.?
You might be tasting and smelling molasses, but you/your brain associates what you are actually smelling, with the smell of molasses. If it is an off-flavour, it probably is something else. Maybe your beer is too young and not done fermenting yet. Recipe, malt, hops, yeast, pH, water composition, etc. will affect your beer in many ways.