We saw that thumb captions are shown in the extract if an image is in the first paragraph. Is there a way to remove it? tried to add "figure" + "figcaption" (MW 1.40) to wgExtractsRemoveClasses with no success. Manally adding the "noexcerpt" class to the image did work.
Topic on Extension talk:TextExtracts/Flow
On which wiki does this happen? What version of MediaWiki are you using?
<figure> is already part of the list of elements to remove. Since <figcaption> is inside of <figure> it will be removed as well. Maybe your wiki's configuration modifies $wgExtractsRemoveClasses in an unexpected way? Maybe your $wgParserEnableLegacyMediaDOM configuration changed, but TextExtracts wasn't updated?