While Bulgaria is part of the EU, it's not part of the Schengen zone, meaning they don't have truly "open borders".

There's full freedom of movement, so it's an open border. The Schengen zone is no border.

it’s not an “open border”. on the contrary. there are actual physical borders between schengen countries and the rest of the eu. whenever you enter/exit schengen you have to pass border control.

If your passport shows you're an EU citizen, you're allowed to enter. So it's an open border for EU citizens.

that’s not how schengen borders work. it’s not an open border. it’s an actual border. and yes, you can be banned from travelling into schengen even if you have an eu passport.