Webp files can contain EXIF information, but we currently do not extract this EXIF information to store it in the metadata column for the file
Example file: https://commons.wikimedia.org/wiki/File:Universiade_(大运)_Exit_A_F1_(2022-08-16).webp
This file contains EXIF information, but the this exif information is not extracted from the file and stored in the database.
https://commons.wikimedia.org/wiki/Special:ApiSandbox#action=query&format=json&prop=imageinfo&titles=File%3AUniversiade_(大运)_Exit_A_F1_(2022-08-16).webp&formatversion=2&iiprop=timestamp%7Cuser%7Cmetadata%7Cextmetadata
Shows that the information is not extracted.
This should be implemented in the webphandler class.
https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/core/+/refs/heads/master/includes/media/WebPHandler.php#99
The specification for webp riff is
https://developers.google.com/speed/webp/docs/riff_container