Automatical permanent residency

I am from an EU country. I have lived here for 9 years, all the time being employed and paying taxes. Every 5 year I need to go to the commune and renew my residency permit. Last time, this was a pure formality as nothing had changed in my circumstances. Eg. same address/employer etc and I was just handed a new(paper) card.

I have adjusted very well to life here in Belgium and would like to stay for the longterm - one reason for example to continue to build up pension rights, private and public. My question is, should I be so unlucky to loose my job for example just before I have to renew my 5 year residency permit, what happens? I think I can find another one, but it might take a little time. Is it so now that since I am an EU national I have automatic permanent residency? If so what do I need the 5 year residency permit for, obviously I understand I need to be registered with the commune, but it is a bit unclear to me what the rules are. Do I need another card, like an ID card now

I am sorry for the naive questions, but I believe things have changed a bit since I first arrived here

Thanks in advance to all who respond