Whilst looking into the api calls that slackin uses, I noticed it is using channels.list, which is deprecated and noted to stop working in February 2021. From my understanding of the code, all running slackin instances will stop running, erroring whenever being initialised.

https://api.slack.com/methods/channels.list

Although, with slack no longer providing a way to generate legacy tokens, this further complicates the future of slackin.

N.B. slackin-extended has (unintentionally?) resolved this issue back in January, version 2.0.0. Although it still has the same issue with legacy tokens.