There is no new original Starlight lighting-mod release for Minecraft 1.21.11. The original repository is archived, and the standalone public release line belongs to the 1.20.x era.
Use project identity before version identity
First confirm that a page describes the Spottedleaf Starlight lighting-engine rewrite. Only then look at the supported Minecraft and loader versions. Reversing that order can make a 1.21.11 modpack look like a continuation of the original mod.
What the archived line supports
The historical Fabric line reaches Minecraft 1.20.4; the Forge line reaches 1.20.2; a NeoForge 1.20.4 project was also published by the same author. None of those facts create an original 1.21.11 release.
Why forcing an old build is a bad test
Starlight modifies deep lighting and chunk behavior. Loader compatibility checks may stop an old file immediately, but even bypassing those checks would not make the underlying mappings and game internals compatible.
For server operators
The maintainer’s later direction for newer server-side optimization is to use Paper derivatives or Moonrise rather than expecting new standalone Starlight releases.
For client users
Choose performance mods that explicitly list your exact 1.21.11 environment. Treat any “Starlight 1.21.11” download as a separate project until its authorship and code lineage are verified.
Related guides
Continue with the 1.21.10 notes and the search-ambiguity guide.