Earlier quoted context omitted.
It might be GPL but I would guess it's not AGPL. AGPL requires you to open source the code to run the service. They've not done that. Their legal people are likely on top of this. It's not hard to run a SaaS and avoid all AGPL
Didn't debian change to the AGPL version of ghostscript in a patch security update? If you use imagemagick or other pdf related libraries that maks use of ghostscript, this could happen easier than you think.
Mostly, yes[0]. Parts of the package are under BSD, others FreeType license, others GPL etc.
I don't know which ones are used in imagemagick, so I can't say whether AGPL "infected" it.
[0] https://metadata.ftp-master.debian.org/changelogs//main/g/gh...