There are three aspects to your situation:
- Your right to work in Brazil
- Your right to work in the EU / for an EU company
- Taxation of your income
You write you are a software developer. It will possibly make a huge difference if you will be hired as an employee by an EU company while you are living in Brazil (which would legally be possible but according to my experience in the field very unlikely) or if you will be providing a service on a contractual basis to a company in the EU, i.e. you will just agree on a compensation and write them an invoice for your services.
When it comes to working as an employee, it may depend on the country you're hired in, but at least when it comes to Germany they would treat you like any German employee when it comes to taxes.
If you will provide a remote service as a self-employed person, then all your taxation and paperwork will be in Brazil. And you don't even have to be an EU citizen to provide services from Brazil to an EU country.
A way in-between might be to establish / keep a registered company in the EU which you will use to write your invoices. That would most likely make your live easier with certain big accounts in the EU as they are frequently highly sceptical against making contracts with non-EU companies.