Can anyone diagnose why I went into limp mode here?
 

I also got a tire puncture on the same lap, not sure if the two are related. I have a 2015 auto and the code thrown was U0073. Here's the lap:

https://youtu.be/yki-5k7qDN0

The limp happens at about 1:47. The tire was punctured by a rather large piece of metal, you can hear it in the later half.

By the way, this happened at Chuckwalla, my very first trackday ruined by this rather early, I had one session before this, and this was the first lap of the second session. Everyone was very helpful, they tried to find a tire for me but couldn't, so I ended up having to drive on the spare donut crawling on the highway for an hour and get a new tire. They also are giving me a free trackday, so not all is lost and I do want to go back, this time with a new set of wheels and tires and a full size spare or two.

Were you running any data logging and did the car eventually take itself out of limp mode when you reset/cleared codes or is the code persistent?

I was running torque app, it found the same code other scanners did, the U0073, and it is not persistent, we cleared it and everything seems fine.

OBD will trip limp mode sometimes if there's a bad connection to a device plugged into the circuit that's cycling on/off or connecting/disconnecting repeatedly. I ran into this with the 86Nanny I used to have; the connectors were faulty in that case (easy fix once it was sorted out.)

I would recommend not leaving the scanner plugged in all the time, the OBD2 can be a primadonna about that sort of thing. Start the car then plug it in when necessary otherwise leave it out, this is a common issue. I believe it will act normally for a few power cycles but it'll probably pitch a fit at least once per track day if you leave it in all day.

https://www.ft86club.com/forums/showthread.php?t=61958

Everything else seems fine, hope your next track day goes better!

That makes a lot of sense, thanks.
To anyone wondering, apparently from that thread linked, the problem is running the Torque app while the car is starting, not the adapter itself.