In case it helps, I attached a screenshot showing the context menu "Add Search Engine" option for the Wikipedia search field in Firefox 140 Nightly. Related article: https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox
Bug 1968233 Comment 1 Edit History
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~~In case it helps, I attached a screenshot showing the context menu "Add Search Engine" option for the Wikipedia search field in Firefox 140 Nightly.~~ Disregard (see below) Related article: https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox