Edit: Thanks!!!

Hey! It's me again who tried to help you yesterday or earlier today with the long message, or at least try haha.
It didn't let me respond to your message so figured I'd just leave another review.

Anyway, I just realized how dumb I actually am. I didn't realize the add-on would create another sub-menu in your context menu when you right click on an image!!
I saw the "Convert and save your images as" add-on feature! I feel like this should have been obvious for me but for some reason I went straight to the normal "Save As" and I thought it would automatically convert images from there to .png and .jpg.

So maybe others are running into the exact same problem I did and didn't realize there was another menu for it haha. At least I think so.

But yeah, right now, extension works perfectly so far!
However on Twitter it seems like when you try to save an image using the extension you have to type in file extension manually. Reddit and Facebook it seems to work fine though!
Here is the Twitter image I tried to save, but I think it happens pretty much with any Twitter image
https://twitter.com/sylvainsarrailh/status/1388105998011875330/photo/1

I am going to guess where people had this problem the most in my opinion was maybe Reddit, it's so far the only place where I saw it saved images as .webp.
Twitter and Facebook by default saves the images in .png or .jpg when you do the original Save As way.
Unless of course you need more help, then I won't leave another review haha.
But yeah, good luck and keep up the good work!

I'd love to use this extension, from the looks of it it's incredibly convenient. For this reason, I've installed it - but none of the quality sliders are working for me. I can't move them at all, no matter what I try. For as far as I can tell if I read other reviews, maybe it's because I'm using Windows 7?

[Edited after reading the response of the developer]

Thank you for taking the time to test it. Your explanation is spot on and clarifies why I can't move the sliders. The only file types I want to convert, are .bmp and .webp ones and I've set both to be converted to .png files. The rest says 'Don't convert' (though I thought it was logical for their sliders not to move, I just didn't understand why the other 2 wouldn't). I get it now. (And just to be sure, I checked and noticed that if I say I want a file to be converted into a .jpg one, I'm able to move the slider just fine.)

Thanks again for your time, and for your response. It was helpful <3

Musthave! Userful, simple, compact. Very pleasher to use.

Thank you! Webp has been driving me nuts, I like to save most images as jpg.

Windows 7. Firefox Developer 84. Everything is work. Thanks!

Using Windows 10 as a platform, but any time I share a downloaded image, my friends, slack users can't use it. I've been manually converting using ImageMagick convert *.webp *.jpg, but that got tedious. This plugin is an extremely convenient workaround for what should be a setting in Firefox. Thank you!

you saved my life

Does exactly what it says. PERFECT!