foreign (IT) workers pay a max of 30% income tax the first 10 years they work/live in The Netherlands

Not quite... the first 30% of your salary is tax-free:

https://www.belastingdienst.nl/wps/wcm/connect/bldcontenten/...

Not actually foreign, you just have to have lived more than 150 kilometers away (straight line) from Dutch borders for at least 2 years before your employment begins.

I heard of 8 years. In 5 years you can optionally apply for Dutch citizenship and if it's approved 30% rule is gone.

It used to be 10 years but was reduced to 8 a few years ago.

You keep the 30% rule after you apply for citizenship though. It even applies to native residents who haven't lived in NL for more than 10 or 20 years.