Update 134.0 has a bugged middle mouse button

I always use the middle mouse button (pressing the scroll wheel) to open and close new tabs, but since the update, it doesn't work anymore and now types "=" if the cursor is in a text field. For context, I use an MX Master S3, mapped with Logi Options+. Anyone else having this issue? How do I roll back to the previous version?? SOLVED: It was a bug with Logi Options+, not Firefox. When I hovered over the tab for the presets I had for CaptureOne, I noticed it also said Firefox. So seems something weird happened there. Deleted that preset and the issue in Firefox went away. I couldn't find a way to delete this thread, though.