I quit reading the book before the meeting and now I actually finish books
For about two years I would show up to my Thursday night book club in Portland having read maybe 40 pages and just nod along while everyone talked. I got good at guessing themes from the back cover and the reviews I skimmed on my phone in the parking lot. Then a guy named Dennis asked me point blank what I thought of chapter 12 and I had nothing, just dead air in front of 11 people. Now I read the whole book no matter how slow it goes, even if I have to set a timer for 25 minutes a night. It changed how I argue in there too, because I can actually point to a page instead of repeating whatever the loudest person claims. Half our fights used to be about stuff nobody had read past the intro for. Does your group call people out for faking it, or does everyone just let it slide?
That timer thing is smart, because the problem with fake reading is you never build the habit, you just build the excuse. In my group we mostly let it slide until someone gets called out by accident, like your Dennis moment, and then they either quit showing up or start actually reading. So the call out kind of does the work for you, even if it feels bad in the moment.