There is no way a file for server output filters can break a site. All it does is compress the text in all files on deployment it can’t remove any of it or alter it though. More than likely your cache or lack thereof did it. This plugin doesn’t play nice with the most popular cache plugin (that will remain nameless) not having a defined and total setup. A site of mine started breaking as a result of this. But when I deacticated and reactivated gzip it was back to normal and I had no further problems. Basically it can’t not work as advertised.