Early fall 2023 it certainly feels like I caught Verizon discriminating against Firefox. It was a CSS issue in their payment portal where some information wasn't rendering as a DHTML popup but at the bottom of the page. You could still pay your bill, but to an untrained eye it looked broken. I reported it and was sent to "Executive Custom Service", which would never acknowledge the problem. They would call once a week and make some statements like the problem was on my side and they couldn't reproduce it at all, to which my BS meter kept responding "I don't believe you." After several weeks of this, the issue mysteriously disappeared one Saturday morning, with no further word to me. I'd also complained to my state PUC (this was a landline bill) and think the added pressure helped convince them to do the right thing, even though the PUC has no online jurisdiction.

At the time I hadn't thought to go back to tech support and ask somebody there to simply try it with Firefox. Then Verizon would have been pointing fingers at themselves.

Any Verizon developers here? I'd love to know the real story.