If you previously installed a customized version of Firefox with Yandex or Mail.ru, offered through partner distribution channels, this release removes those customizations, including add-ons and default bookmarks. Where applicable, your browser will revert back to default settings, as offered by Mozilla. All other releases of Firefox remain unaffected by the change.
Bugzilla: 1759009 - Update Distribution Config
lemmy.ml: Firefox v98.0.1 removed Yandex search option and used misleading bug name to hide it
Actually you’re right, it’s well hidden.