Please update to 7.1.1 and
unzip /share_int/shaders.tar.xz to /share/shaders
with this shader as source, i was able to fix the crt-pi shader for RPI4
I tweaked some values , so that the shader looks as close as the one on RPI3 (reduce moire effect, deactivate mask for real colour)
I didnt found a source for the barrel and mask shader (maybe special recalbox shaders?), so this was the only one i could fix for now.
Just copy the crt-pi.glsl file to /recalbox/share/shaders/lr/crt-pi
Hope i could help 🙂