@BlackYps
yeh, i have the same experience with Proton Gallium Nine Extras and AMD GPU with basic Ubuntu 18.10 drivers.
it seems to be working but i cannot see much difference.
it might be some lack of implementation on the Mesa driver side (it have to support the directx calls). and it supports it but not fully(?) just doesn't render everything.
i had the same experience with vanilla Wine4.0 that had the Gallium patches merged into btw, not just Proton...
i don't know what's going on.
one thing i noticed that enabling the bloom renderer in the game settings gives you much more effects (but not all).
for example you still won't have the UEF T2 bomber (Janus) napalm effect:
https://www.youtube.com/watch?v=bBnlmecW0igalso, pls check that you are using the RUN file that actually points to the Proton Gallium Nine Extras wine.
mine looks like this:
https://pastebin.com/ASdeijtg