The implications are the variables are conflated and the conclusions are overblown.

It should come as no surprise that acute trauma and injecting a foreign substance would cause a relatively significant immunological response. The issue is that for the “chronic phase”, which is where the novelty of this research lies, the evidence shown is far from difinitive compared to the story being told and what results are shown aren’t overly significant.

Even if you 100% believe the paper the conclusion is that the effect of getting tattooed is, arguably, similar to catching the flu once. However, the paper itself tried to obfuscate that so they have a more impactful result and the marketing/outreach/media site that was linked here doubles down on it trying to sell the story of “tattoos==illness and death”!!!