Why is GDP per capita so high in Italy but salaries so low?

There seems to be a discrepancy in Italy between salaries and GDP PPP per capita.

Based on Numbeo, UK has a purchasing power(based on declared salaries) 36% higher than Italy. Judging by number of italian workers who come to the UK, and visiting both countries, I can confirm UK is richer. But GDP PPP per capita is the same.

I inderstand GDP includes government spending and investment, but is that accounting for the whole difference?

On a similar thread someone was saying ‘GDP should not be deflated using PPP because GDP is holistic (included government spending and investing) whereas PPP is limited as a consumption deflator’. But assume the extra income is invested directly into the country/economy, instead of being paid as wages, it should still he visible as an investment?
Can someone elaborate further?