Template Template:Extension do automatically load data from extension.json file. But what when is code new version in another branch? It is i.e. branch form-support of the Extension:AccessControl. This code is actualized up MediaWiki main branch, but code main branch of the extension was developed from my old obsolete version. Every not use accesslists based on template parameters for it I do extra branch, but users don't know because template not download extension.json from it.
Topic on User talk:Pppery
The template reads its data from Module:ExtensionJson, which is updated by a bot operated by Bawolff. You need to ask him, not me.