As Consul Connect is disabled by default it has me wondering, is it safe to suddenly enable it in a production cluster or are there any potential (negative) repercussions to consider?
Before utilizing Connect in production I would recommend reviewing the Connect in Production guide and implementing the suggested configuration changes – as well as those specified in the Connect Security checklist. Ideally you should first configure these settings in a non-prod environment so that you can understand the operational impact, and develop a plan for safely rolling out those changes to production.
Enabling Connect on the Consul servers (see Connect Configuration) is the easy part. Configuring the associated changes required for a secure deployment and developing operational expertise with those sub-systems is a bit more challenging.
I hope this answers your question.