You may have received the following email:
Your org has been identified as having users or integrations still connecting to Salesforce using TLS 1.0 encryption protocol.
You are wondering if Heroku Connect is a contributing factor.
Heroku Connect is fully compatible with TLS 1.1.
You should be able to look up which users or integrations are still connecting to Salesforce using TLS 1.0 using either the New TLS Protocol Field in the Login History or creating a list view or report