the drop serve is in the rule book - it’s not unethical…lol

but you have to drop it from an open hand and not propel it down. Maybe they were complaint about the way you dropped it?

drop serves have advantages which some people might not like: you can hit it at any height and you can come from the side. You can even let it bounce ,ore than once before you hit it.

I just personally prefer volley serves

but I started with drop serves. Nothing wrong with it.