I have had similar experiences too. To me, HTMX felt like a wrapper around vanilla JS's .fetch() or jQuery's AJAX calls except one just litters the HTML with specific custom HTML attributes.

.fetch() has no issues returning server-side rendered HTML and has a lot more options and freedom than what HTMX provides.

I do not think HTMX is a bad library by any means. I just can't see what it buys over vanilla JS.