The moved the design to a more modern process. You can see that smaller lines sizes and shrunk dimensions can also reduce robustness of parts.

 

that would be total non-issue if the part number changed. but keeping the part number the same while changing specs (many changed for worse) is unforgivable.

 

Motorola did exactly the same thing to us back in the 1990s with the MJ15015. We'd been building a reliable power amplifier for years and suddenly they started blowing up. At first they blamed us, so we cut the tops off the transistors and found that all the ones that had blown up had a different die. I think they changed from hometaxial to something different.
After some argument they admitted it and "compensated" us by giving us a tiny discount on the MJ15003, but by then we'd cut the tops of enough transistors to find out that the MJ15015 was a higher voltage 2N3055, and the MJ15003 was in fact a 2N3773, which was much cheaper; cheaper than the discounted MJ15003.

 

CEO to engineering:
“We are going to fall short on the quarterly profit predictions we made to Wall Street. Do something NOW!”
Engineering obeys.
Stocks soar.

I know I am being sarcastic, but just a little bit.

 

In Dave's video at 21:23 you see the new DS on the left. It says there are input protection diodes. According to this video there are not:

 

I think they changed from hometaxial to something different.

Probably planar, which generally had a lower secondary-breakdown value than the hometaxial (mesa) process devices.
So your experienced failures were probably due to secondary-breakdown in the planar devices.

There was a similar issue when the 2N3055 was changed from hometaxial to planar.

It would seem really unconscionable for a manufacturer to change the internal structure and thus the operating characteristics of a device without changing the part number in some manner (such as adding a letter to the end of the number).
But many have done it.