That’s a pretty good question. And likely there won’t be a definitive answer until there’s a decision from court.
I think in these cases one should try to understand what the IPR holder had in mind when they picked AGPL and not for example GPL or Apache. Trying to find loopholes might just get you into trouble in future.
That’s the difference about the AGPL - you have to open source the things that call it too. Putting it in a microservice is literally the thing that AGPL was written to prevent you from doing to work around it
I’m getting downvoted, but this is the stance of the company behind a popular AGPL library mentioned in this comments page based on emails I received from them after asking the same question.
AGPL requires open-sourcing your entire project (authentication, payment platform, etc) just to link to a backend PDF processing library.
AGPL does not have a linking exception.