Tested: it works the way I suggested. Thanks again!

Thank you very much, you are obviously right. However, I can't give up hoping that I still could use my existing data, as comparing the dates as numbers in my head would return the same results? Of course using your meta_query method, instead of filtering in php. Or am I completely wrong?

Echoing $startDato displays like this: 20230131

@nmr That is strange. As I state in the description, the code works in a template file. But not when I try to trigger it by a hook. In the first case, the log is filled with info, and the posts get their status changed. In the last case, nothing happens.

Seems like a good piece of advice. I'll try that one.