Wei Lun Make sure to use medium's import tool, otherwise, you'll harm your website. Through their importer you get a canonical link which notifies crawlers that the content belongs not to Medium but to you.
Google trusts websites with the higher domain more. In your case, Google will think you're stealing content from Medium.
The best thing to do is wait for 2 weeks before republishing posts on other platforms, so that crawlers pick you up first.