I think I lost some written text because of this extension - the text was there, but after submitting it in Teams, half of it was gone.
In jira comments it messed up words if I tried to correct them.

There is clearly a significant memory leak issue on Firefox. As a paid subscriber, I am no longer able to use it. Firefox freezes and becomes unusable.

I am a premium user, and unfortunately the Firefox extension is causing serious issues. It consumes up to 32 GB of RAM, which makes my computer freeze and eventually restart on its own. This is not an isolated case — it happens on two different computers, so it’s clearly not a hardware issue on my side.

This makes the extension completely unusable despite paying for the premium service. I would expect much better stability and performance from a paid product. Please investigate and fix this as soon as possible.

It used to be a 5 stars plugin, but since the January 2026 update, whenever I switch this plugin on, firefox crashes on my Macbook. It totally eats all the memory. I reported it as a bug more than a month ago but haven't heard from them. So, for now, it will stay switched off.

It's even worse than the built in spell checking of FF.

It isn't shown on here, but if you click the link in their "about" section, you can see that they now use AI to scan and check your text, which is probably why I've been getting so many errors in it lately, including ones for proper nouns that weren't there before.

In short, don't use it. It doesn't work like it used it, and as it is using AI, there is the potential for it to be using your own text to train models. Uninstall it if you have it already.