Bandwidth exemption for site

Hey there! To answer your question, Netlify does not exempt Open Source websites from overage charges like bandwidth, build minutes, etc. However, since this is your first time going over, I’ve applied a courtesy credit to your account to cover 80% of the bandwidth cost for this month. In the future you will still be subject to bandwidth costs.

I’m not sure if you’ve seen this yet, but we do have a guide in the forums here for managing your bandwidth:
Reducing Bandwidth Without Reducing Traffic!
Take a look at that if you haven’t yet and maybe you’ll find some helpful pointers!