Thanks Jenny! Doesn't really answer the question as to WHY it decided to appear today making me feel like something was changed or wrong.
That's what "occasionally when I sign in to highlight what's new and suggested" means.
Microsoft just decided to try to push out some new feature or ad that you have no interest in, and this causes the "welcome screen" to appear.
Looking like it's infected with adware or a virus seems to be a "feature" of Windows 10.
I know that I had some settings set to not show stuff but right now it is all set to show everything (notifications) so... back to the drawing board I guess.
Turning off your desired settings is a "feature" of Windows update.
You need to check them after every Windows update to make sure they haven't gone back to default.