Using a diode is not that uncommon for that kind of voltage drop.
But we are not really talking about voltage drop here, we are talking about current limiting. A series diode won't work in this situation.
Over the years you'd become familiar with debugging issues, I use MCUs since 2004.
So you are essentially a beginner. Microprocessors have been around since the 1970's and these LCD modules date from the 1980's. Some of us have been working with them all that time.
Don