Just a guess, but I assume magazines are part of physical press. I know a lot of millenials (according to this definition of millenial) who buy magazines for their interests, be it music, games, geology, astronomy or history. A lot of times it overlaps with having been in tertiary education and I assume Gen Z would show similar statistics if you asked someone who was pursuing a masters degree or a doctorate.
I think this chart is %change from before covid to after covid. This chart doesn't say they are consuming most physical but they have increased the amount of physical media since covid. But then why no negative percentages?
It is the percentage of people that have started (or increased) consuming that type of content. So 19% of millennials started consuming (more) physical media. It says nothing about the millennials that stopped or consume less or the same as they did before.