Are we sure this co-incides with the deployment? Or has someone changed a page onwiki at the same time?
There weren't any changes to the extension at all
Similar for it's partners in crime that is ZeroBanner https://github.com/wikimedia/mediawiki-extensions-ZeroBanner/compare/wmf/1.29.0-wmf.16...wmf/1.29.0-wmf.17 and also JsonConfig https://github.com/wikimedia/mediawiki-extensions-JsonConfig/compare/wmf/1.29.0-wmf.16...wmf/1.29.0-wmf.17
Seems a lot like someone changed something on the wiki page, badly... Or a core change
That seems to be a recurring theme of some of these "store config on wiki" solutions we've been using. They don't handle bad input well and cause errors much further down that we have zero way to gauge the severity of.