I’ve encountered this and more issues with the WebComponent sp-textfield, particularly the change and input events are not working for me - which is a huge blocker.
The plain <input> control has its own quirks for me - it seems to work fine on PC but on Mac there sometimes is a weird focus issue where text input isn’t possible until I dock the panel at least once (??).
The most “stable” input control so far for me has been the Spectrum UXP Widget <sp-textfield> one. I mean, it also has theming issues, but at least it seems to be functioning fine otherwise.
^^^ Turns out that the focus issue also happens on the <sp-textfield> widget on Mac…
But… this actually only happens when I programmatically want to set focus to it (via a element.focus() call in JS) AND when the panel is in a floating state, docked it does not give issues… weird stuff.