Why is my SharePoint List not supported?
How to fix so that I can connect in GET ITEMS flow this list?

Why is my SharePoint List not supported?
How to fix so that I can connect in GET ITEMS flow this list?
You aren't connecting to a SharePoint list. That URL is for a OneDrive location. Did you create the list in SharePoint lists but save it to MyLists? If you did then the list was created on your OneDrive for Business, not a SharePoint site.
But the question is what action are you using in Power Automate Desktop? I know there is a new SharePoint connector, but I don't think it has a Get items. Can you explain the context a bit more?