Since the new version was deployed to lemmy.ml which allows blocking instances I tried to block an instance.
When opening the drop down and enter the name/url of the instance (or even a part of its name) the list is then filled with a seemingly random list of instances but not the instace I searched for.
I tried in a desktop browser (Chrome on Windows) and in a mobile browser (Vivaldi Mobile, which uses Chromium as base), same behavior.
Since I don't use GitHub I report it here.
Yep, this is the list.