Yes...battery regeneration is limited to protect the battery from overtemp.

The car's brake controller calculates how much braking will be done by regeneration and how much by the regular hydraulic brake system. If the battery's state of charge is high, or if the temperature is too high or too low, it will limit how much energy it can accept safely. If you brake softly/coast, the car will regen as much as possible back to the battery. If you brake harder, the friction brakes will do the majority of the work instead.

Of course other things effect it too--for example, the Vehicle Dynamics Control/ABS systems. If the car detects that a front wheel is about to lock up under braking, or if the car is about to slip, then it will redirect braking torque to another wheel. Imagine if you were driving on a slippery road and only the front brakes were working...this is what's happening when the generator is doing the braking. So, it has to account for regeneration's effect on stability control too.

For temperature relationships, remember that the AC is powered by the HV battery--so the hotter it is outside, the more the battery is getting used to power the AC, which leaves less available for driving the car, which means the engine must then come on sooner to assist under acceleration or to maintain the battery's state of charge. And since the battery is getting used more because of AC, its temperature increases, which also leads back to its ability to accept regeneration.

It's a delicate balance to maintain driveability, climate control comfort, fuel economy and reliability all at the same time!