https://github.com/violentmonkey/violentmonkey/issues/2254

extract-violentmonkey-backup.rb

require "json"
require "fileutils"
require "cgi"
include FileUtils::Verbose

folder = 'C:\Users\hyrious\OneDrive\Apps\Violentmonkey'  # <-- change to your backup folder place
index_file = 'Violentmonkey'
target = File.join __dir__, 'ViolentmonkeyExport'
mkdir_p target

a = JSON.load_file File.join folder, index_file
info = a['info']

info.each do |part, meta|
  filename = 'vm@2-' + CGI.unescape(part)
  i = meta['position']

  data = JSON.load_file File.join folder, filename
  File.write File.join(target, "#{i}-#{filename}.user.js"), data['code']
end