It’s surrealism, so it’s not meant to be realistic. Likely, the candles are returning to nature but that’s my guess. It might just be the user(s) of these candles instead.

Magritte’s work frequently displays a collection of ordinary objects in an unusual context, giving new meanings to familiar things. […]

René Magritte described his paintings as “visible images which conceal nothing; they evoke mystery and, indeed, when one sees one of my pictures, one asks oneself this simple question, ‘What does that mean?’. It does not mean anything, because mystery means nothing either, it is unknowable.”

Wikipedia