initializationOptions with rust-analyzer don't seem to work

[cyclopanic]

var lspServers = [
    {
        name: 'rust-analyzer',
        filetype: ['rust'],
        path: 'rust-analyzer',
        args: [],
        syncInit: true,
        initializationOptions: {
            cargo: {
                targetDir: true,
            }
        }
    }
]
call LspOptionsSet({
    aleSupport: true,
    noNewlineInCompletion: true,
})
call LspAddServer(lspServers)

setting rust-analyzer.cargo.targetDir to true doesnt seem to work. file lock is still being blocked and rustanalyzer and cargo are still using the same directory (using vim9script)