I use Slack integration for several my jobs—mostly for notifications.
I recently received this message from Slack:

Hi Joe,
The Conversations API is a one-size-fits-all replacement for a variety of APIs used to read and write information about channels, private channels, direct messages, and multi-party direct messages. On February 24, 2021, Slack will end support for any methods preceding the Conversations API.
Since your apps use these legacy methods, please ensure updates are made to avoid interruption. Here’s how you can prepare for this change:
• Use this tool to identify your affected Slack apps.
• If users expect your app to work in channels of any kind, please verify use of the Conversations API by following this guide.
We're here to help. Please direct your questions to our support team by emailing feedback@slack.com.
Thank you,
The team at Slack


https://api.slack.com/docs/conversations-api