I also don't just mean outages like this... it's clear that Microsoft GitHub has been cramming a bunch of new stuff into the UI and not really treating it with care. I notice very amateur UI bugs, misalignment, bad spacing, overlapping elements, etc. all the time now. It was clear that old GitHub passed through a professional designer's eye quite carefully (or maybe just a developer with extreme attention to detail).
Seriously. Example: the "merge pull requests" button. If your repository requires linear history and the current type of merge is unavailable, the entire UI element turns grey instead of green. It looks like you can't use the button at all, but the dropdown arrow still works to select a valid type of merge (which then turns the entire element green).
It's a small thing, but it causes confusion by making it appear that the change cannot be merged, and it makes you wonder how much testing they do.
These little things keep piling up as they focus on shiny new features which rarely work correctly at launch (looking at you, code search...)
Please, GH product managers. Take a break from breakneck new features, and give your devs time to clean up and do some preventative maintenance.