I hold an EU passport of a Schengen area member state and travelled on a day trip to Hungary. In Hungary, I walked to and then along the outer Schengen border until I reached a border crossing, where I ended up between the border checkpoints of the two neighbouring countries. During my walk along the green border (i.e. a grass strip, without any fences or other barriers), I took a large number of photos of the grass strip and border markings (stones).
Believing that I had done nothing illegal, I went to the Hungarian border checkpoint and explained that I had not left the Schengen area and was legally allowed to be in Hungary. To prove this, I showed the border police officers a photo of the grass strip I walked on and a border marker, which showed that the grass strip was still inside the Schengen area. I had to hand over my phone, and the border police officers went through all the photos I took that day, then I was instructed to irrecoverably delete all my photos from the border area.
This was during Coronavirus travel restrictions – I was allowed to cross the border between Hungary and my home country, but apparently travel between Hungary and the non-Schengen neighbouring country was still generally prohobited. Travel to the non-Schengen country would not normally require a visa for me.
I was eventually allowed to pass the border checkpoint, but one of the border police officers told me that I will face a hefty fine for the photos I took, with a friendly smile that made me unsure whether he was serious or just joking. Another border police agent told me that being in the immediate vicinity of the outer Schengen border is prohibited by itself, but none of them seemed to know the exact legal situation particularly well.
What consequences should I fear now?