I appreciate you have put effort into this, and you have gone out of your way to make it safer, but if the extension were to become malicious at a later date, expanding permissions (and relying on users brainlessly-clicking accept) or using an exploit or sidechannel would undo any of that.

The downside of browser extensions is that they are operating within a massive codebase, and thus have a huge attack surface if they decide to become malicious.

For what its worth, I commend your efforts here, its just near impossible to trust any peice of software not backed by the reputation of an established company/developer.