Ty for your message on Fly.io.
In case someone is interested, on Fly.io I asked “Can I use Esbuild version 0.19.11 instead of 0.17.11 with Phoenix LiveView?”.
This was after I successfully flattened the nested CSS in local development, after the help in this Elixir Forum topic. In production with Fly.io it did not work. Not yet, at least. Also after trying version 0.17.18.