What do you mean? I'm talking about macOS feature that works in every application. But not in Firefox. How to fix it?

Hi

I saw this in the Apple support forum - https://discussions.apple.com/thread/250623071 that recommended this add-on for Firefox:

https://addons.mozilla.org/en-GB/firefox/addon/textfast/

I saw this addon too. But why I need addon if my OS support this feature by default? What's wrong with Firefox and why text replacement doesn't work?

It may have been the case that many people have not requested this as a feature or perhaps it has been put to one side in favour of other features that have been included in Firefox.

The people who answer questions here, for the most part, are other users volunteering their time (like me), not Mozilla employees or developers. If you want to leave feedback for developers, you can go to the Firefox Help menu and select either Share ideas and feedback… or Submit feedback…, depending on your Firefox version. Alternatively, you can use this link. Your feedback gets collected by a team of people who read it and gather data about the most common issues.

You can also file a bug report or feature request. See File a bug report or feature request for Mozilla products for details.

See:

• 1149826 - Mac "text replacement" feature does not work in forms

(please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html)