For completeness, here is the reply from one of the KDE developers: https://lists.sr.ht/~sircmpwn/public-inbox/%3CCAGeFrHA7FyqR2...

(It doesn't appear in the thread because it's been forwarded)

EDIT: and here is a blog post about EGLStreams from another KDE developer (2016): https://blog.martin-graesslin.com/blog/2016/09/to-eglstream-...

Here is a follow-up blog post from the same author (2017): https://blog.martin-graesslin.com/blog/2017/10/plasmawayland...

Here are some (technical) discussions on wayland-devel about EGLStreams (2016): https://lists.freedesktop.org/archives/wayland-devel/2016-Ma...

Here are some recent IRC logs from #wayland, also discussing EGLStreams: https://dri.freedesktop.org/~cbrill/dri-log/?channel=wayland...