I think people overstate the direct influence a bit, but the feedback loop is undeniable. BookTok, and romance/erotica Tok in particular, thrives on immediate, shareable 'moments'—the quote, the trope, the spicy scene snippet. That's bled into what's getting published and promoted. You see more books engineered for that clip-ability: a very high-concept premise you can sum up in a caption ('grumpy x sunshine but he's a mafia lord and she's his therapist'), explosive, visually describable scenes, and tropes that function like search tags.
It's not that the stories are shallower necessarily, but the pacing has shifted. Slow-burn is still huge, but the 'burn' often has more frequent, intense flare-ups to generate those talking points. The whole 'why did it go viral?' calculus now includes 'does it have a 15-second moment that will make someone's FYP?' That shapes everything from cover design—bright, graphic, less clinch—to chapter structure. It’s also created this fascinating meta-layer where the reader's anticipated reaction—the gasp, the screenshot, the duet—is almost baked into the writing. It's a very different kind of intimacy than the old-school, solitary paperback experience, but it's a powerful, communal one.