I lived in Singapore for 4 years. It’s not illegal to chew gum in Singapore. It’s illegal to sell gum. It’s illegal to litter which includes dropping gum anywhere, but in the garbage bin. You can possess gum and chew it all you want.
I forgot about that, they reached a trade agreement where they can now sell medical gums, but still no gum just for fun.
So possession of gum is legal, but not selling it.