Unlike other products, self hosting only gives you the same as their basic version. So even keeping it up to date will never match their premium offering. This is of course fine, just making people aware before they spend time setting it up because they don't make this very clear (I had to find a Github issue to get this conformation in writing)

The free self-hosted version you can download from https://languagetool.org/download/ lacks all the premium rules (several thousand rules for English, German, French, Spanish and Dutch) and AI-based rules.[1]

[1]: https://github.com/languagetool-org/languagetool/issues/6750