I am running testing:
$ pacman -Qi xorg-server
Name : xorg-server
Version : 1.20.9-1
Description : Xorg X server
Architecture : x86_64
URL : https://xorg.freedesktop.org
Licenses : custom
Groups : xorg
Provides : X-ABI-VIDEODRV_VERSION=24.0 X-ABI-XINPUT_VERSION=24.1 X-ABI-EXTENSION_VERSION=10.0 x-server
Depends On : libepoxy libxfont2 pixman xorg-server-common libunwind dbus libgl xf86-input-libinput nettle
libpciaccess libdrm libxshmfence
Optional Deps : None
Required By : nvidia-340xx-utils sddm
Optional For : None
Conflicts With : nvidia-utils<=331.20 glamor-egl xf86-video-modesetting
Replaces : glamor-egl xf86-video-modesetting
Installed Size : 3.64 MiB
Packager : Philip Mueller <philm@manjaro.org>
Build Date : Tue 25 Aug 2020 11:54:01 AM EDT
Install Date : Wed 26 Aug 2020 07:14:01 AM EDT
Install Reason : Explicitly installed
And Manjaro Settings Manager > Hardware Config says I have video-nvidia-340xx and pacman says I have installed it with Linux 5.4
$ pacman -Qi linux54-nvidia-340xx
Name : linux54-nvidia-340xx
Version : 340.108-60
Description : NVIDIA drivers for linux.
Architecture : x86_64
URL : http://www.nvidia.com/
Licenses : custom
Groups : linux54-extramodules
Provides : linux54-nvidia-340xx
Depends On : linux54 nvidia-340xx-utils=340.108
Optional Deps : None
Required By : None
Optional For : None
Conflicts With : linux54-nvidia-390xx linux54-nvidia-418xx linux54-nvidia-430xx linux54-nvidia-435xx
linux54-nvidia-440xx linux54-nvidia-450xx
Replaces : linux54-nvidia
Installed Size : 4.71 MiB
Packager : Helmut Stult <helmut@manjaro.org>
Build Date : Sat 22 Aug 2020 11:40:18 AM EDT
Install Date : Sun 23 Aug 2020 03:21:42 PM EDT
Install Reason : Explicitly installed
Install Script : Yes
Validated By : Signature
And so far, so good.