I have been told that a brass fitting connected between the copper
and galvanized will avoid the problem. I have also heard it doesn't
help. Did they use brass fittings to join metals?

Bob

This is not correct. You won't have a problem with galvanic corrosion
between the copper and brass (anodic index difference of 0.05V), but
you will have a problem between the brass and the galvanized steel
(0.80V). An anodic index difference of 0.50V or less is recommended in
a controlled environment (like a house) to avoid corrosion.

BRW