@Substring Isn't a full blackscreen anymore, it has the recalbox footer and stays black. But yes, config should be standard:
##Hostname or IP-address of host to connect to
##By default host is autodiscovered using mDNS
#address =
##Video streaming configuration
width = 1920
height = 1080
fps = 60
##Bitrate depends by default on resolution and fps
##Set to -1 to enable default
##20Mbps (20000) for 1080p (60 fps)
##10Mbps (10000) for 1080p or 60 fps
##5Mbps (5000) for lower resolution or fps
bitrate = -1
##Size of network packets should be lower than MTU
#packetsize = 1024
##Default started application on host
#app = Steam
##Default used mapping for streaming
##Searched for in $XDG_DATA_DIRS/moonlight or /usr/share/moonlight and /usr/local/share/moonlight
##Mapping can also be user overrided in $XDG_CONFIG_DIR/moonlight or ~/.config/moonlight or current directory
#mapping = mappings/default.conf
##Enable selected input devices
##By default all available input devices should be used
##Only evdev devices /dev/input/event* are allowed
##To use a different mapping then default another mapping should be declared above the input
#input = /dev/input/event1
##Let GFE change graphical game settings for optimal performance and quality
sops = true
##Play audio on host instead of streaming to client
#localaudio = false
##Select audio device to play sound on
#audio = sysdefault
##Select the audio and video decoder to use
##default - autodetect
##omx - hardware video decoder for Raspberry Pi
##imx - hardware video decoder for i.MX6 devices
##sdl - software decoder
##fake - save to file (only available in debug builds)
platform = default
##Directory to store encryption keys
##By default keys are stored in $XDG_CACHE_DIR/moonlight or ~/.cache/moonlight
keydir = /recalbox/share/system/configs/moonlight/keydir
##Load additional configuration files
#config = /path/to/config