That is down a bit. I'll still use it because it's enough for me. I don't get a lot of miles on my oil changes. Since ZDDP is depleted due to heat and pressure the more you have to begin with, the longer it lasts.
The LESS zinc you start with the sooner your oil change interval needs to be. You have 300 PPM less in the above example.
If we took that 900 PPM oil and compared it to an oil with say...1500 PPM, fresh out of the bottle there is ZERO protection difference between the two oils. None.
One oil will be offering protection longer than the other.
Again, buying an oil based on it's zinc content is bad policy.
Cheap oil isn't cheap and expensive oil isn't expensive in the grand scheme of things.