This is just the latest step in the evolution of a relatively old ('80s) phenomenon of describing people's faces in comparison with foods. It all started with しょうゆ顔, meant as "the typical Japanese male face", Higashiyama here being the prototypical example [cont] https://twitter.com/vonMandelbrot/status/1354840415069900800
This is of course because soy sauce is a staple of Japanese cuisine and because the typical/ideal (good looking) Japanese man has a narrow face with slightly wide eyes, well-defined cheekbones, and a tall (but not long) nose.
Then came the ソース顔, a more Caucasian type of face with a strong jawline, larger eyes, longer nose, and so on.
Around the same time (afaik) the 塩顔, with slanted eyes and a very thin profile and nose, became a thing.
Around the same time (afaik) the 塩顔, with slanted eyes and a very thin profile and nose, became a thing.
And then, of course, there came hundred of variations. The implication is not that a person with a mayonnaise face likes mayonnaise, but that they look like the visual translation of mayonnaise's taste. One more important thing worthy of note is that a food's taste in Japan is
often described as either 濃い (thick) or 薄い (thin). A creamy chocolate cake is 味が濃い, underseasoned pasta is 味が薄い and so on. In general 濃い is something like "decadent". チーズ牛丼 is very, very 濃い. Similarly, faces are also described as 濃い or 薄い.
A big nose, full lips, creased eyelids, thick eyebrows, a big chin, sunken eyes etc., are all 濃い. I think having this linguistic similitude between how tastes and faces are described is what, at least in part, helped the whole "condiment-face" thing become as big as it is.