unofficial patch
a patch for a piece of software, created by a user community without the involvement of the original developer
en-GB/ˌʌnəˈfɪʃl ˈpæt͡ʃ/
en-US/ˌʌnəˈfɪʃəl ˈpæt͡ʃ/
a patch for a piece of software, created by a user community without the involvement of the original developer