More frequent than just a down-pointing arrow is the downwards-pointing arrow in a triangle. I am not sure if the two symbols refer to the same. The arrow in a triangle is an ancient Masonic symbol. You can find a beautiful one in the Mutus Liber Latamorum (1765):
It is even on the title page of Les Plus Secrets Mysteres Des Hauts Grades de La Maconnerie Devoiles Ou Le Vrai Rose-Croix (1766):
There the image is published with the last (7th degree) called “Le Noachite ou Chevalier Prussien”. A few pages further, there is an image quite like the one above.
In the collection of 81 degrees that became the French Rite, the text of the named degree explains the symbol:
Q. Why do the Christians wear a triangle? R. in memory of the temple of Phaleg
Q. why the inverted arrow!
A. in memory of what happened to the Tower of Babel; the apron and the gans are in memory of all the workers of the tower, the black cord is a mark of sadness
Also (some versions of) Memphis Misraim has a 21th degree called “Patriarch Noachite” with a downwards pointing arrow in a triangle as emblem. The image all the way at the top comes from a 21º AASR “coat of arms” for a degree that is called: “Patriarch Noachite”. “Noachite” does seem to be the connection here.
Top: A. & A. R. The intermediate Degrees 19º – 29º A.C.F. Jackson (1982)
Middle: Mutus Liber Latomorum (1765)
Bottom: Les Plus Secrets Mysteres Des Hauts Grades de La Maconnerie Devoiles Ou Le Vrai Rose-Croix (1766)