Hm hm, are you sure? And what is the difference between personal data and content? My pictures are pd or content? And if I publish them?

Source: https://en.wikipedia.org/wiki/General_Data_Protection_Regula...

Now, obvliously, the content may contain personal data, or possibly be personal data (if it's pictures of people) and in that case I assume it would be covered.

I'm not convinced your interpretation is correct. GDPR Article 4[1] states that "personal data" means "any information relating to an identified or identifiable natural person (‘data subject’)", so it covers anything you produce that's somehow related to you.

[1] https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CEL...

In theory even the personal writing style might be considered "personal" as it could be used to identify individuals, but I don't think that lawmakers thought that far.

Well, as said, if the content itself can be considered personal data then sure.

My entire point was that "personal data" as defined in Article 4 is any data related to you, not just names, photos and so on

I could be wrong (i'm no expert) but i remember part of the GDPR is about "data portability" and is exactly that: you should easily be able to export all the data you've provided. https://gdpr-info.eu/art-20-gdpr/ I would assume this includes articles you've written.

Personal data can be used to identify you. Email, Full Name, Address, Nationality, Spoken Languages etc.

Some of these are very direct like your name and address. But since other personal data can be combined to create an identifying fingerprint of you it may or may not be covered.

There's a gray area in between of course were you really need to check the legal situation, but public content on a public forum is definitely not covered.

I'd say that while a single comment on a forum might not be enough to identify you, the sum of your comments can easily do (because of pieces of personal information you let slip in this or that comment); then everything you write must be considered personal data, unless there is a way to tell apart or remove the personal information from your comments.

Think about pictures: the picture of a landscape you took on a holiday doesn't identify you, but other pictures in your library might do (they contain faces, places, etc.). All together, the pictures can tell who you are and where you've been and when and with whom.