Did Aaron Davis give off any red flags?

There are a few hints here and there that there's more to him that immediately meets the eye:

1. Aaron brings Miles to "a place he knows" for him to paint, which is coincidentally just outside the secret Collider entrance. This area is closed down, and Aaron has never before shown it to Miles, despite them having ostensibly spent much time together; this implies that he's only recently become aware of it himself, but there's no "normal citizen" justification given for why he'd ever have to travel here. When you view this through the lens of him being hired by Kingpin for the new project, it all falls into place.

2. While travelling to the closed down section of the subway, Aaron hops over a fence in a very gymnastic fashion, and Miles is left scrambling to follow behind. This is an unusual degree of skill for an average person to have. Most physically fit people would still hop over a fence in a safer and more controlled way, rather than peter parkouring. When viewed through the lens of him being a highly skilled villain and wanting to show off for his nephew, this also falls into place.

3. While spending time with Miles, Aaron gets a mysterious call about work and has to drop everything immediately to deal with it. He never mentions where he works or what his responsibilities are. This is similar to how Peter Parker behaves in other incarnations of Spider Man: when he hears an emergency occurring, he comes up with an excuse to suddenly leave so he can secretly deal with it. Aaron, however, speaks on the phone as if he isn't simply fulfilling a duty, but is actually beholden to someone else. When we view this through the lens of him being called to deal with an emergency at the Collider, this also falls into place.

4. Finally, Miles' dad doesn't approve of Aaron's life choices, for reasons that he never elaborates on. However, he also (ostensibly) doesn't approve of Spider Man's vigilantism. Altogether, this strongly implies that Aaron is either a criminal or a vigilante, even if Miles' father doesn't know all the details.

After rewatching the movie again, I realized a visual clue -- a piece of artwork inside Aaron's apartment somewhat says "the Prowler", a literal clue, including a tiger motif, similar to how the Prowler is themed around a ferocious cat tracking down its prey.