They do it often enough such that closely following an AI around a bend at speed is a lottery where I find myself expecting to get brake tested at any second. It's not pleasant. Anyway, they shouldn't be doing it at all. Once is once too many.
I think FM AI has had a free pass for far too long because it was so much better than in GT, which let's face it, isn't hard. Its deficiencies are pretty glaring now as other titles have upped their game. Drivatars in their current format don't seem to be the answer.
Usually defend Forza's Drivatar system especially with the mid corner braking, because most of the time there is traffic ahead or the racing line turns red for me (even though I know I don't to brake in that line bend) and I assume that most players actually brake in that point so of course their drivatar does too, especially on difficulties lower than unbeatable. Some tracks are worse than others, like tracks that don't have a lot of Drivatar data yet like Circuit of the Americas, Sonoma, Watkins Glen or almost all of the wet and night tracks. Those aren't great excuses, but it will get better naturally over time because a) there will be more Drivatar data on the newer tracks soon and b) a lot of the more casual players stop playing the game after a few weeks, leading to their Drivatars being pulled less often into races because of how the Drivatar-rewards system works.
But man, yesterday...?! Yesterday I was done with excuses!
1976 F1 cars against Pro Drivatars on Circuit De La Sarthe, it was
teeerrible and I even had the spoilers set as low as they get, so the AI should have an advantage in high speed corners(assuming the AI always uses the standard tune for spoilers). With sim damage on and rewinds off..., even I have to admit that it would have been
unplayable (assuming you don't drive as carefully as my mother and are okay finishing in 10th place); especially between Mulsanne and and the finish line... Not just mid-corner braking but also too early braking without traffic in sight and evading invisible obstacles when I'm about to overtake, completely unpredictable behavior. I switched rewinds on, otherwise I would have stopped playing after 3-4 restarts.
Maybe Turn 10 should just manually iron out the Drivatar behavior for the worst corners on most of the tracks, even if that makes the bad Drivatars better than they should be based on the recorded data of their real life counterpart.
Edit:
This picture is from the 8th lap of the Mazda MX-5 Cup showcase event (and not just in that showcase event but in general on Laguna Seca), and this Drivatar has been here since the 2nd lap.
I've had this too, he tried to evade the 1st lap jam by going inside and it would have worked in FM5, but not in FM6 with that tyre wall there.