Preview mode publishes changes to live site

In customizing my page styles and layout, I find that many times clicking "Preview" actually pushes those changes live. Yikes! This defeats the purpose of Preview mode.

I did not hit Save, or Save and Publish, just Preview yet about 1/2 the time my live site now has the changes I only made in Preview. I certainly don't want my live site to be where I test my new code.

Has anyone else seen this?  It certainly makes the entire development / testing area of Freshdesk useless. I should probably just dump all the code into a regular web dev program and work from there.