Probably due to treesitter modules for many languages compiled in. AFAK Treesitter's codegen is unfortunately a share nothing between different languages. So a dozen language parsers can easily cross upward of 200 MB.
Binaries for dynamic libraries of tree-sitter (usually compiled with C compiler) would be smaller than that. For example this [1] .so bundle for 107 different grammars is ~137 MiB.
Unless by "compiled in", some in-lining of the C code into Rust codebase is meant.
