Isn’t Chrome itself malware? 
Sure, but I assume this would also be a problem for the various chromium based browsers.
That’s a good question.
It seems to me that there are multiple problems with extensions as a whole:
- Uniquely identifying an extension. For example in Chromium right now, searching for “save image as type” brings up two, maybe three, seemingly different but similarly or identically named extensions. and a few more that have similar enough names that they could easily be confused with the one that is the subject of the article. So which one is the dodgy one? (Because it has already been disabled, it probably isn’t one of the ones listed.) I understand that extensions have a UUID but that isn’t going to cut it i.e. too user-unfriendly.
- Extensions can change from non-malicious to malicious.
Chromium doesn’t seem to want to let me install extensions at all anyway - because I have Chromium installed but not Chrome installed. I have zero intention of installing Chrome. So really that suits me fine. No extensions means no dodginess.
This functionality should probably be just part of the browser anyway. If you can “save image” within the browser, you ought to be able to save it in whatever formats the platform supports for conversion. However I understand that “the road to hell is paved with good extensions”.
And, FWIW, on my computer, double-clicking a .webp file launches eog and the image views OK. So probably no need for this extension anyway (for this specific scenario).
All good points. I didn’t know chromium blocks extensions because I soured on extensions around 20 years ago and haven’t given them a lot of thought since, but lately I’ve been starting to get tempted. This good gone bad story has brought me back to my senses even though this particular feature is well below my threshold. (And I almost always configure browsers to ask where to download, which trivially provides the opportunity to change the extension.)
One of the lost old time browser configuration options I miss most is blocking clicked links opening in a new tab, which of course can be overridden by right clicking. (I especially hate it when a link is rendered in a new tab but the browser remains on the original tab, the worst of both.) An extension that restored the ability to blocked left clicked links in a new tab would sorely tempt me except for the outrage of having to jump through hoops to restore basic functionality from the early days of tabbed browsers.
Do the Firefox “Tab” settings not accomplish at least some of what you want?
(I prefer to open links in new tabs.)
EDIT: You might also peruse about:config to see if there are any tab behavior options.
No, that is a different option that I also use when available, but it is not needed as often. I almost always want to stay in the same tab when I follow a link, then use the back button. I am a heavy user of the back and forward buttons and really hate web pages that require 7 clicks to get back from following one link (and even more sites that disable back button).
I’ll give it a look, but I’m not hopeful.
See if this works: How can I force links to open in the same tab instead of a new one? | Firefox Support Forum | Mozilla Support
Unfortunately, back may not work (for a range of reasons, as you acknowledge).
… which is why I like (we are all different, right?) “open in new tab” (whether explicit or implicit). Because then it takes exactly one click to get “back” (i.e. I close the new tab) and it is highly reliable. 
That does mean that sometimes a browser window has a lot of tabs open but unless you are short on RAM, that’s not a major issue. Firefox even allows you to group up open tabs. And you can also open a new browser window if you do temporarily want to keep all the tabs ungrouped and open but it is making it messy for something else that you are trying to do.
Not really. Yes, it changes the extension (the name of the file on the disk). But that in no way changes the semantics of the file contents. It doesn’t convert the file.
The problem is: There was a window of time where .webp files were appearing on the web, and were supported by the browser for display, but were not supported by very many other applications. So if you saved the file, you wouldn’t be able to open it subsequently e.g. by double-clicking in a file manager or by opening from within another application.
So a sensible solution was to introduce a browser extension that would convert a .webp file on the fly to a JPEG file (JPEG having very wide support) as part of the process of saving - and PNG would be an alternative to JPEG.