transition said:

I asked the interactive encyclopedia “when did margarine become available around the world as a substitute for butter”

“Margarine first became available as a substitute for butter in 1869 in France, and gradually spread throughout Europe, North America and the rest of the world during the late 19th and early 20th centuries”

wow, that far back

There you are then.

Although in some parts of the world, notably the USA, margarine wasn’t initially allowed to be coloured yellow, as it might be mistaken for butter.

So the makers used to include a little package of yellow dye for customers to mix into the marge themselves.