Baby not gaining weight

Hi is it normal for 1 year old to not gain weight? My baby been 9.4kg for about 3 months now, never gain. He is currently close to 14 months old. He’s somewhat picky with food, doesn’t eat that much solid & he drop his milk intake. Currently he drop even more to about 400ml is this normal?? Wondering does parent give baby food salt & sugar at this stage to make food tastier? Will appreciate any tips on what type of food can make baby gain weight thank you 🙏🏻 #firstmom #FTM #baby