There's no built-in roll back, but there may be some other options.

First, though, do you recall what version you were doing before? The Troubleshooting Information page should have a "Show Update History" button in the first table to research that. See: Use the Troubleshooting Information page to help fix Firefox issues.

Here is the update history

Okay, it's hard to know whether Firefox 133 can work with your profile after it was updated to Firefox 136. I wouldn't want your files to get corrupted.

What do you think about using a separate edition of Firefox on the side for the site that requires it? You could share bookmarks and some other data between them using Sync, so it would be slightly more convenient than using Edge, Chrome, etc. for the site. What do you think?

The other edition would be the Extended Support Release of Firefox 128, which you could download from the following page. Please use the custom install procedure to install it into a separate folder so it doesn't overwrite your main installation.

• https://www.mozilla.org/firefox/all/desktop-esr/
• Custom installation of Firefox on Windows

I mainly use the browser for that purpose so I don't mind losing the updated version, I will try that and hope that helps. Thank you!

Just to be clear, I recommend preserving the existing installation so you can Sync your data between them.

understood, I will install it separately to avoid future issues