Hmm, do you mean in the web console?
I know Firefox has a bit of a reputation for being rather precise in how it handles web standards compliance. So, it'll show comparatively many warnings and errors, if you don't keep to the web standards.
This is actually quite useful for web devs, because it means, if Firefox is happy with your implementation, then it's relatively likely to run correctly on all browsers.
Based on the title, I thought it would just bleep out the customer voice. That would certainly not make the customer less angry. 🙃