What is the tiny double on/off icon appearing on my iPhone Lock Screen?

Lock Screen on opening today there is a upper right corner line that suddenly appears and an oddity symbol fades in and out. Looks like an on/off switch on top of an on/off switch. Swipe does nothing. Tap does nothing. Can you explain? What to do now? Feels invasive!

[Re-Titled by Moderator]

Original Title: tiny off on double symbol anomaly?!