The thing is that this is not something that happens, I remember when I first started using Linux, I got lots of weird problems like that, eventually they stopped happening, and for a while I thought Linux had gotten way better, until one day I was going through some backups and I found a xorg.file with a typo, and then I had the revelation that I had been breaking random stuff without realizing it.
You mentioned that the monitor doesn’t work on a fresh Ubuntu install, but does it work on the live iso? You also mentioned having to run several commands and tweaks after installation on Ubuntu but not on Fedora, did the monitor work before those tweaks or could it be that one of those caused it?
I know such errors can be frustrating, and if you’re happy with Fedora there’s no reason to look back. BTW this is not a “you’re using your system wrong”, but you might be causing the issue without realizing it, I know I was when I was in your shoes, and probably would be angry at people telling me that because I was sure I hadn’t done anything.