* myADP had some kind of bug preventing firefox authentication that lasted months.
* Elan financial redid their credit card site for fidelity visa and had a CSS bug that hid the card total balance. This lasted for about a month.
* bitbucket (work required) had this bug that prevented pages rendering in firefox. It was some kind of JS client side bug and it impacted a bunch of people in my company. After months of support request they gave us some console commands that opted into an experimental feature which resolved the issue. This one was especially frustrating as they kept telling us to just clear our cookies and delete our profiles.
* Some random IRS system I had to use for either requesting a tax transcript or validating my identity just didn’t work.
It’s actually been so frustrating my coworkers joke anytime there is a bug I’m experiencing that it must be another Firefox only bug.