The README for the PuppetDB module on the forge has a syntax error in the "multiple node setup" node definitions - https://forge.puppet.com/puppetlabs/puppetdb#multiple-node-setup. Node names in node definitions can't be variables.
This was fixed in https://github.com/puppetlabs/puppetlabs-puppetdb/commit/f9ab009010f4af4acfa162ecd45b72190601358e 9 months ago, but there hasn't been a release of the module since then, so the forge documentation is still wrong.
Also the embedded database is no longer a thing but the forge README says it is. https://github.com/puppetlabs/puppetlabs-puppetdb/commit/417e02881bd33d28d31f0897e8e72564c6a4846f fixed that.