Error Message about Unavailable Fonts

Hello,

This morning I opened some FrameMaker files that I worked on last week. I didn't add any new fonts or do anything exotic with them, and no one else had access to these files. Only me. Yet, this morning I opened several of these files and got this message:

What does this mean? And how did I suddenly acquire unavailable fonts when I have not touched these files in nearly a week?

As a side note, I got a message today from Adobe asking for my feedback about my recent cancellation of Adobe Creative Cloud. Neither I nor my employer has made any moves to cancel my subscription. This happened once before (Adobe decided, unceremoniously of their own whimsy) to cancel my subscription. A bizzare conversation with their customer service personnel ensued, and all was fixed. But I'm wondering if the "cancellation" has anything to do with suddenly not having access to certain fonts?

Adobe has been in the Twilight Zone for the past couple of years, after being a stellar, reliable company for decades. Not sure what is going on.