Scientific publishing is possibly one of the biggest scams there is. The public funds scientists to do research who then haven't to pay the publishers for the privilege of publishing with them (no royalties! just the opposite!) The publishers who then send the papers out to reviewers who do what is essentially the entire point of the process, peer review, for free (reviewers almost never get paid) and then, once accepted for publication, they then charge exorbitant amounts for the same scientists (who want to do research, which requires knowing what your colleagues have done) to read that work.
Honestly, say what you will about Big Pharma, Disney or whoever else people usually complain about when it comes to abusing the state of intellectual property rights, but the sheer brazen balls of charging the people who actually do the work not once but twice, and charging everyone else as well (that's three!) Let's just say I'm glad cOAlition S was launched—and their current plans? Getting rid of APCs as well? *chefs kiss*. But yes, the exact models are something that are still currently being worked on, see PLOS: https://theplosblog.plos.org/2023/06/moving-away-from-apcs-a...
(Also covered, somewhat ironically, behind a paywall at Nature: https://www.nature.com/articles/d41586-023-03342-6)