The working solution with Adblock:
wikipedia.org##[class$="mw-ui-icon-element"]
help.adblockplus.org/hc/en-us/articles/360062733293#elemhide_attributes
Unfortunately, more advanced solutions do not work, e.g.:
wikipedia.org##[id="vector-page-titlebar-tocv-label"]:not(.mw-ui-quiet)
wikipedia.org##[id="vector-page-titlebar-tocv-label"][class$="mw-ui-icon-element"]