gatsby-plugin-s3: Wrong Metadata for files in subdirectorys

I am encoding all my assets with brotli. All files are suffixed with .br. For example index.html -> index.html.br This happens with all file types, for example html, json, js, css,…

I tried both of these params:

        params: {
          '**/*.br': {
            ContentEncoding: 'br',
        },

and

        params: {
          '*.br': {
            ContentEncoding: 'br',
        },

My index.html.br in the root folder gets the following Metadata on S3: Cache-Control: public,max-age=0,must-revalidate Content-Encoding: br Content-Type: text/html

My /kontakt/index.html.br gets this Metadata on S3: Content-Type: application/octet-stream