I grepped a bunch and at least the following projects still use the removed icons:
mediawiki/extensions/BlueSpiceBlog Uses 'newspaper' icon in resources/ve/ve.ui.BlogInspectorTool.js. It needs a dependency on 'oojs-ui.styles.icons-editing-citation' to continue displaying the icon. (Filed T202336.)
mediawiki/extensions/ProofreadPage Uses 'clip' icon in modules/ve/node/ve.ui.MWPagequalityInspectorTool.js. (Filed T202337.)
mediawiki/extensions/VisualEditor Uses 'settings' icon in modules/ve-mw/ui/pages/ve.ui.MWSettingsPage.js. (Apparently this has already been spotted by our excellent QA engineers and reported in T202101. Thank you!)
oojs/ui Heh, we still use the 'settings' icon in demos and documentation. Oops… (Filed T202338.)