It's not the same issue. You got a grey screen after loading the payload. In my case I regain signal when in the shell and can boot into the OS but I get a black screen when it tries to load the OS GUI. I did try your method before of disconnecting the HDMI as soon as the payload loaded and plugged it back in after 10 seconds but It never regains a signal. ctr+alt+F6/F2/F1 still doesn't regain signal.
Hmm, okay then my method doesn't work for your monitor/tv as we're having the same problem.
Because my shell is visible too and it loads into the os but as soon as it loads the OS gui a gray screen comes up. I'm using ITmania's fedora32 and his background behind the tron lady is gray. Maybe you're using a different distro and it's showing you black? (it's an image not pitch black lack of image is what I'm suggesting) alas, my method doesn't work for you. Sorry to hear that.
Just as a final measure can you use the 5.3.7 kernel in my zip I uploaded for someone else?