Hi, in my experience staghorn is an easy algae to remedy, you just need to fix whatever is out of balance and it will go away on its own.
Twice I've had it appear, the first in a newer setup that was very iron rich, dirted using the amaco red clay method, plus I was over fertilizing with a fert that has a good amount of iron. I wasn't doing any water changes (snail tank), and when I did a 50% change, and stopped the ferts, it made its first appearance, popping up on some guppy grass that I clipped out. I dimmed the light for a few weeks until I could start back up with the ferts (new shrimp) and it didn't come back on any plants. However, with the iron rich water, and a good amount of light on my HOB outtake, it was growing in my outtake for awhile. Switching to lighter fertilization caused it to go away eventually.
The second tank it appeared in it was caused by the light. I was using a nine watt led flood that is not made for plants. This bulb is just wack, no matter what I do with it, it grows algae, different setups create different algae, at any height. The bulb is too powerful, plus I feel like it isn't a good spectrum for plants, 6500k, but nothing grows well with it. I could see the staghorn was concentrated where the light was the most powerful. I started using a different light, and it took a little time and it just disappeared.
Powerful light seems to be a necessity for it, so you might wanna look at how long your photo period is, but also how intense your light is. If you threw things off with your ferts I'm sure that could help trigger it.
Hope that helps