Arc has a similar feature, but last I checked it used ChatGPT. Firefox runs a local model, so it avoids the privacy issue.

I have no problem with this in principle. The question is, does it suck? Document summary is a use case LLMs are well suited for, but it's still highly application-specific. I've seen great summarizers and I've seen garbage summarizers. Hopefully Mozilla's implementation is not as lazy as most others.