For anyone else struggling with this: I FOUND THE ISSUE!
It’s a bug straight from SwiperJS. As soon as I reverted to the previous build, everything works like it should.
In short, I changed the 9 to an 8, like so: <script src="https://cdn.jsdelivr.net/npm/swiper@8/swiper-bundle.min.js"></script>
becomes <script src="https://cdn.jsdelivr.net/npm/swiper@9/swiper-bundle.min.js"></script>