I don't know about red flags as far as the player... I have concerns about his father acting as agent ; wanting to control the Combine process in saying that they will not participate in the medical evaluations. That they will only do it with private meetings with who "they" think are worthy. Also, the father met with the NFLPA and asked to have the rules changed so Caleb's rookie contract would not have the existing limitations in value. Caleb in interviews, when asked if he has a plan B if not not drafted 1st, said he has no plan B. He said he deserves to be #1, a bit of summarization there... It came off as a bit arrogant IMO. I know every player is going to do what is best for their future, but most stay within process that all other players must go through. I will chuckle if the Bears go another direction and WIlliams falls a couple of spots.
I have to respect that different people (and different organizations) will have different things that they consider "red flags."
For me, I would probably categorize them like this.
-Medical/injury concerns
-Off field character issues
-On field character issues
-Lacking certain physical traits. This is less of a "red flag" than it is a "I'll take that guy off my draft board" thing. Bryce Young being so small, would be an example of this.
For me, none of the things you list would raise any concerns. It's mostly just updated versions of Elway & Eli Manning.. with some Lamar Jackson sprinkled in. None of those QBs had any problems, imo.
Things worked out fine, on the QB front, for the Chargers.. not so much the Colts. So.. when deciding to pass up the guy who is clearly the best QB in his class, that's a risk they have to factor in.