This is the solution as I recall (stolen from reddit post cited at bottom):

Step 1: Right click an open Picture-in-Picture window. In the context menu, select "More Actions" -> "Configure Special Window Settings...". This will populate most of the window settings for you.

Step 2: Click "Add Property..." and select "Window title". The newly added row's text field should read "Picture-in-Picture". Change the dropdown option from "Unimportant" to "Exact Match". (All PiP windows in Firefox use this title and by making it Exact Match the rule shouldn't affect any other Firefox windows.)

Step 3: Click "Add Property..." again and this time select "Keep above other windows". The dropdown in the newly added row should be set to "Apply Initially". Select the "Yes" radio button if it isn't already. (As a note, I think that didn't work for me as I have it set to "Force" rather than "Apply Initially")

Step 4: Click "OK". That's it. No more manually setting Keep Above every time you open a PiP.

Since doing the above it's just worked without issue, though it was annoying that it was broken in the first place.

https://old.reddit.com/r/kde/comments/osjt3p/firefox_wayland...

Maybe I'm missing something, but Picture-in-Picture has worked for years in Wayland Firefox for me. You do have to enable it in `about:preferences`, there's a toggle called: "Enable picture-in-picture video controls"

Are you sure it wasn't running under XWayland? Firefox has had wayland support turned off by default until just recently.

I'm sure because I have a high DPI screen and the font rendering in Xwayland is jarringly noticeable.

On which Desktop Environment/wayland compositor? I am pretty sure Firefox Picture in picture works as intented (tiny window, stays on top of things) on GNOME's wayland session, and on Plasma 5.27.x I was able to make it work with a few KWin rules set by GUI (I would love to share the details, but I don't have my Plasma machine with me currently).

To my knowledge there currently isn't a solution, but it is being worked on/discussed: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/m...

That is the state of a lot of things in Wayland. They seem to remain that way for a long time, alas.

What compositor? I use Hyprland and Firefox/Chromium Picture in Picture, and as far as I can tell, works as expected. I just hit the PiP button and it pops the video out into a new tiled window that I can toggle floating if I want. Just tried on a windows machine and, as far as I could tell, it was the same.