Hi

Thank you for your question, that does indeed look a little odd.

How many tabs did you have open? If looks more like an 8 that has been cut in half...?

What is the device that you are using? Would I be right in thinking it is running Android 11?

Have you changed any of the default settings, such as font size?

I had 3 tabs open at that time, and I'm running on a oneplus 8 Pro, android 11 indeed, on their default font settings which is different from the stock android font, correct.

But it normally does show the "3" (and "8" for that matter) correctly.

Do you have any add-ons installed?

What other apps have you added to your device?

I have dark reader (disabled at that point) and unlock origin installed.

As for what apps I have installed, that's a list of more than 100 which I don't think will be very useful. Just think the standard social media, some home automation like ring, nest, Google home and home assistant, banking, shopping and news

I'd it were a third party app that'd be influencing Firefox, only lastpass comes to mind. I do not have anything installed that alters the ui in any way (with the exception of lastpass which draws over apps).