I can answer this, you will lose your PR status if you do not stay in Singapore after certain years.
In my example, I am late 40s, I left Singapore in 2006, initially I can still login CPF account to check the balance, but after 7 to 8 years I start discovered my Singpass cannot be used anymore and of course cannot check cpf balance, thus I start sending cpf via email and request for cpf statement alternate year. I was told and read many articles said PR will never be expired, I think it is not true if you do not renew your re-enrty permit after certain years, to be confirm I came to Singapore in years 2016, go to cpf office to verify with them, and was told the system show me I am no longer an PR.

So, in conclusion, PR can be expired if you do not work or stay in Singapore for long.

anyone knows about PR renewal? since topic has been derailed.. i guess why not derail it further

example my frined has PR due for renewal next year around july . however end of this year he plans to go EUrope for PhD for 2-3 years
so he will be oveerseas for soem time
however he will be paying tax next year because this year he worked, and next year mid year will be due to pay taxes for this year (2023 taxes are to be paid in 2024). but 2024 he will be full time studying hence no tax .

since he is still paying taxes next year, that should work for him right? plus past 5 years he has been paying more than average taxes, in fact id say he is paying top 10% amount or more (e.g his tax per month can pay 2  blue collared workers salary) and he can always return after studies to continue contributing to SG. the only issue is that nowadays everything is computerized, and u cant justify all this to the computer which doesnt give a damn.  he even got some letter of appreciation during pandemic for volunteering during Sg's worst time in the past decade, the COVID 19 pandemic.....

anyone has similar stories of successful renewal?the reason to get PR is so that he can easily find a job after studies. but also heard EP does not need any quota, actually his pay qualifies for EP easily, but worried that EP will be given less preference compared to PR