There should be a way to allow extensions to execute only on specific websites like the Site access option in Edge does, this improves extensions usability and may also enhance privacy.
I also want this! I am surprised firefox is one of the last browsers to get this, I'm very wary of extensions like darkreader that have access to the full content of the sites you are on, in chrome at least I have it as an opt-in and I can exclude sites.
This should be implemented in a flexible way so uses may specify either a whitelist (extension works on only these sites) or a blacklist (extension works on all sites except ... ).
It's puzzling that this hasn't already been implemented, since it's a simple way to dramatically reduce the potential harm malicious extensions can cause. I have nearly a hundred extensions active (and, yes... they are all necessary for various use cases) but the majority of them aren't needed on all sites. Another big benefit is greatly reducing the overall count of extension / site accesses. Consider a metric which counts the number of times any extension accesses any site. Currently that metric is basically (number of extensions installed) * (number of sites accessed). Reducing this metric would not only improve security, it would reduce the number of issues encountered caused by extension compatibility and it would also increase overall browser performance, simply by having fewer extensions accessing fewer sites.
The fact that site-specific add-on permissions still haven't been implemented after two years is rather baffling, all things considered. Even a simple site access blacklist/whitelist for add-ons would be amazing.