Automatic downshifting

I was going down a medium grade yesterday and tapped the brakes, got a pretty strong downshift, my first thought was, tow haul must be on for some reason, but that was not the case. My second thought was, after years of driving older trucks with issues, uh-oh what kind of transmission problem do I have now…
Really pleased to read here that the engine braking is a feature also in D, not only tow haul. I’ve been appreciating it while in T/H S4 with the horse trailer, but again didn’t know it was a feature across the board in D.
Do most trucks have this feature now, or is it a Toyota thing? Pretty nice, in my opinion… I haul the horse trailer so often that even when I’m not hauling, I tend to drive like I am, leaving lots of space and never jumping on the brakes if I can help it.
Also read that the Toyota computer will “learn” my driving style, what exactly does that affect or change in how the truck drives?
Thanks so much, really loving this truck.

 

The engine braking is very handy when pull a trailer.