I have the experience of updating to 2004 on 6 desktops, 3 laptops, the experience on all were completely different.
The ancient (at least 12 years old) desktop worked with flying colours, and is up to 20H2 and cumulative update already.
But I had 2 ASUS desktops that refused time after time, eventually the newest loaded but gave a black screen after login, that was fatal as even safe mode failed to work, I had to perform a full fresh install error free !!!!
The other at the 10th attempt at bedtime, was upgraded by morning,
2 other desktops loaded fine first time the others required work around suggested on other threads here.
my main (very new) laptop is fine, my old retired laptop (keyboard faulty) is refusing to down load 2004 despite saying it is available, the other current problem with this laptop is windows search feature not working due to a previous version upgrade. I am stupidly expecting the upgrade to fix the "search" issue, (an attempt at a fresh install keeping my apps failed).
I dread MS announcing an upgrade, most requiring latte nights to fix issues with the upgrade.
Chris