Yep[0], but if you check the revision that fixed it [1] this seems to be a standard QoL change that Firefox already had the mechanism to perform per-site.
Probably because the changes relate to Picture-in-Picture, which is not a standard web feature. Making sure heavily used websites work well seems logical and Firefox doesn't seem to be messing with web standard here, so it doesn't create any kind of technical debt going forward.
Considering that Mozilla is already protecting their users from specific target sites, it is only logical to assume that they are also improving user experience for a website which has 1B+ users.
Edit: I still cannot overcome the fact that both products are owned by the same company.
I was recently reading through the input handling code for firefox on windows. Turns out that some input method editors insert a special character that facebook then deletes, breaking input handling. So they have a special case fix for facebook where they turn that character into a different one.
I guess when you don't have enough market share to force extremely popular websites to fix themselves, you're forced to fix them yourself.
I'd just prefer it to be draggable. I have started using the feature frequently, but the button is often overlaid the next button on other sites as well.
> When a video is uploaded with a batch of photos on Instagram, the Picture-in-Picture toggle would sit atop of the “next” button. The toggle is now moved allowing you to flip through to the next image of the batch.
[0]: https://bugzilla.mozilla.org/show_bug.cgi?id=1610993 [1]: https://hg.mozilla.org/mozilla-central/rev/55aa8b3e0f6a