Please don’t do such mixes … I think it was told to you already in the previous topic, in some other words.
Make sure you set the rendering backend for Compositor to OpenGL 3.1 (your iGPU must be capable of that - otherwise will not work) and that the Translucency effect is enabled. Try with different Plasma Style and Widget Style too.
I was having the same issue until I came across this post and found out after double checking my compositor, my compositor crashed and was no longer enabled at startup. I’d check if this is the issue for you, if “Enable compositer on startup” is still checked in your kde system settings