Mobile browsers will do all sorts of optimization, such as interrupting the network, slowing down the vm, putting it to sleep, caching and uncaching things without letting you know, and without a predictable pattern.
If you use raw JS, you can deal with all kinds of errors manually, put in place recovery strategies, bust caches, etc.
With HTMX, you just get sluggish behavior, or no behavior at all in your page, and you don't know why.
Also like another person said, you expect your state to be the same, like the scrolling placement, but chrome might decide that no, you get a page refresh there, or you are somewhere else in the page on next switch.
In this particular app, I have a raw JS counter, which is updated on the client to make it snappy, and by htmx to keep it up to date with other modifications. But the counter will be off randomly because Chrome messes with it. So I had to manually put many rules to know it's out of sync, and request the sync at the right moment. But the sync may not happen because Chromes decided so. So I should try several times, with exponential backoff, differentiates the different reasons of failures and update the DOM manually while handling various interactions with other components.
At this stage, you are basically coding a lot in JS instead of getting the state from the server in HTML, so having VueJS + VueRouter + Pinia is going to be easier to manage, and you'll get more interactivity and optimistic updates on top.
It's not worth it. Right tool for the right job and all that.
It's mostly on mobile though. On Desktop, the HTMX app behaves perfectly.