GDP PPP is very irrelevant. Not only that GDP is not a very good indicator, but making further adjustments to it (like the PPP) makes it completely useless.
At least nominal GDP has the same measurement unit, even though GDP is not very relevant in itself, and can be inflated by completely irrelevant economic activity.
There are pros and cons to both estimates.
One problem with PPP, is that its reliant on a very low frequency survey (once every 5 years, once every 10 years on some stuff too) for the prices of consumption goods....through what is known as the ICP (International comparison program). This takes me back to debates I had 10+ years ago when I looked into all of this deeply.
In any case that means countries that experience high inflation in these blocks of time between the survey years (and their releases that are another multi year delay after it too i.e why I say 10 years along with the 5 year one).... basically get an outdated PPP multiplier as result....so their PPP amounts can get highly fudged.
You need to have consistent low enough inflation (like say well under 10%, preferably <5%) for the PPP multiplier components to stay more relevant along "the drift" years.