It doesn't really matter. Someone shot at him four to five times with an assault rifle and came pretty close. I couldn't care less about what grazed his ear.
I've always had doubts about that being the bullet. Obviously I'm not an expert, I'm just a guy on the internet so don't take this as anything substantial as this is 100% armchair speculation and I'm fully willing to concede any part of this; but given what I know about the speed of a round fired from an AR-15 and how camera shutter speeds work, I'd assume that if a photographer was lucky enough with their timing like this, that the streak would be significantly longer. These rounds can go upwards of 3000 feet per second, so for the streak to be that small, you'd need an really fast shutter speed. But I don't think this was a particularly fast shutter at all, because there's significant motion blur elsewhere in the photo. The streak also seems to be slightly more in-focus than Trump does, but it's also possible that the photographer had the wrong focal length in the first place.
I dunno, I could be wrong and that could be the most legit photo in the world. It just feels very unlikely to me. It just seemed waaaay too convenient, on top of a rather long list of other individual conveniences that happened that day. I try not to think too much about it, because it's very easy to get conspiratorial about it.
High light condition with short depth of field means a large aperture and fast shutter speed was used. The fast shutter speed was used to avoid motion blur. However, the focal point is in front of the podium, the whole picture out of focus.
A modern professional camera can use shutter speeds as fast as 1/8000th to 1/32000th of a second. The AR-15 has a muzzle velocity of 3000-3300fps. The length of the visible trail is heavily dependant upon relative humidity.
If you want something fucked, it's that the focal point is in front of the podium. The camera almost always does that, not the photographer. AutoFocus is a touch or half push on the button that takes the photo on a full push. Some security agency probably modified the photo to prevent internet sleuthing and ensure they'd control of the narrative.
Note that this is only application of basics. It's not a nuanced or expert perspective.
I could be wrong and that could be the most legit photo in the world. It just feels very unlikely to me.
Papers in my country reported that a sports photographer said about the photo : "Chance of 1 in a million. Almost impossible". Other articles mentioned the possibility of a small animal flying instead of a bullet.