One issue i have with this extension is that it randomly pops up the 'this site appears to be offline' (which overrides the entire page) even when the site actually works (i hit the back button and it appears). I have it installed for some time now and so far i have almost daily false negatives and only once actually it worked as intended.
Also there doesn't seem to be a way to open a URL directly from the extension which seems a weird omission, so i end up going to the archive site anyway since i very often want to find old long lost sites.
It pops up when there is a HTTP 404 status code or similar returned. So these false negatives are likely due to the specific sites that are configured in a wacky way.
(Don't get me wrong, it is still very annoying for the user regardless what the cause is.)
Does it pop up for any 404 error? If so it might be some script or font or whatever resource the site itself is using that would otherwise fail silently. If not... then there has to be some other bug/issue because i get it for many different sites that shouldn't have it.
Also there doesn't seem to be a way to open a URL directly from the extension which seems a weird omission, so i end up going to the archive site anyway since i very often want to find old long lost sites.