Edit: According to Wikipedia, the final stance now is that the wound was caused by a stray bullet.

No link provided, so I looked it up. It’s in the article Attempted assassination of Donald Trump in Pennsylvania, under Shooting (pretty deep in there though):

The upper part of Trump’s right ear was grazed by the first bullet Crooks fired.^{[99][100][101]}

This looks genuinely great, thanks for mentioning it. Here’s their website, with free learning resources.

Slightly off-topic, but you might find the latest video-essay from Contrapoints, Conspiracy, helpful.