Posted: Tue Dec 29, 2020 11:30pm
This is not quite correct.
The only theoretical “requirement “ for EU citizens visiting another EU country is a request to apply for residency if staying longer than 90 days in a row. HOWEVER, if you leave said country , even for a second, this 90 day rule is again reset to 0 as there is NO minimum time required to reset the 90 day rule. In any case, the whole discussion is moot within Schengen , and thus theoretical.
Also, in accordance with EU law , as a EU citizen, you can never be prosecuted/expelled if staying longer than 90 days in a row. Except in some rare cases ( crimes, terrorism,...)
Hundreds of thousands of EU citizens spend over 90 days in a row in Spain, without any problem and without any government making a fuss about it. In reality, the EU and its member states do not care one bit as long as you are not a burden on the local social security and are not involved in social dumping.