Module triggers redirect loop on image styles

I'm not super familiar with how this module or image styles work, but I think those are the two factors in my issue.

We recently launched a site and post-launch the client asked us to require users to login before seeing any content, so we added this module. What we noticed - but not immediately - was that some images weren't appearing any more. It seems like images that were added before this module was enabled continued to work and those that imported from a feed later were not. I assumed we had a dev-to-prod migration issue, but another developer happened to have their devtools open and saw a stream of console errors, ERR_TOO_MANY_REDIRECTS, pointing towards /user/login.

Adding sites/default/files/* to the exemptions fixed the problem immediately.