In my testing, a default configuration of htmx4 (with transitions enabled) seems to block most/all interaction from the page for ~500ms after a request is sent.
An easy way to reproduce this was adding a couple elements with hx-trigger="every 500ms" and watch the page become unresponsive, although it also seemed to affect my ability to (for example) rapidly click a counter-increment button and have the correct number of increments happen, even when working with a low-latency local server.