https://api.slack.com/changelog/2020-11-no-more-tokens-in-querystrings-for-newly-created-apps

On February 24, 2021, we will stop allowing newly created Slack apps to send requests to Web API methods with access tokens presented in a URL query string. Instead, apps must send tokens in the Authorization HTTP header or alternatively as a URL-encoded POST body parameter.

Just when I finally want to try the destalinator!