I don’t think the webkitgtk team would be willing to fix this, also it’s hard to explain the bizarre use case of Emacs to them.

Well, Po Lu has another paragraph under the one you posted:

WebKitGTK is not meant for displaying contents within programs that must display the same widget in more than one location; that is the metier of WPE (wpewebkit.org). Several months ago, I asked for interested individuals to step forth and undertake writing the code to replace WebKitGTK by that library, but was met with silence.

Looks like the better way to fix this is to switch to the wpe library. Webkit is also quite buggy IMHO Ex: You cannot play video when using offscreen rendering, IOW visiting websites like youtube will hang infinitely. Currently no one is familiar with the xwidget-webkit codebase except Po Lu. I’m not sure if he has time and motivation to fix this. (Po Lu is also the Android Port maintainer…)

The reason is that webkit2gtk no longer supports offscreen rendering starting from 2.42.1. I don’t see there is a clear plan in the emacs-devel for fixing this issue. You can see the full discussion here: https://mail.gnu.org/archive/html/bug-gnu-emacs/2023-09/msg01905.html

I think the reason is that newer webkit version doesn’t support offscreen rendering, which emacs relied on. You can report a bug to emacs-devel and ask if the devs have plan for solving this.