[SOLVED] - Why I still need to import react on each jsx/tsx file?

The solution for Meteor v3 and onwards can be found in How to NOT import React with 3.3.0? - react - Meteor Forum

Basically, just create the .swcrc file in root with the following content.

{
  "jsc": {
    "transform": {
      "react": {
        "runtime": "automatic"
      }
    }
  }
}

Meteor already has the speedy web compiler integrated, so it should work just fine with that.