@dangerzone@social.freedom.press
Anecdotally, the only major PDF reader that loads external content by default is Adobe Acrobat. Still, there are various implementations out there, so check what's the case with your PDF reader.
@dangerzone@social.freedom.press
If you have gained access to a document that may be bugged and want to share it with a trusted third-party, it's best to remove tracking codes altogether. Dangerzone does that, in a process that's similar to a photocopy machine: https://dangerzone.rocks/about/