The clear button <button class="mw-ui-icon mw-ui-icon-mf-clear mw-ui-icon-element mw-ui-icon-small clear" title="" style="">Clear</button> doesn't provide values of screenreader users.
It adds to navigation steps needed to search and deleting an input's value is simpler done without this button being exposed for those.
Should be hidden to AT users by adding aria-hidden="true"
It should be possible to pass an option to the Icon element that adds the attribute aria-hidden.
We could add a generic solution (e.g. allow an array of attributes to be added to the parent element) or a bespoke option for the aria-hidden option.
I guess it should default to hidden, unless explicitly stated otherwise.