This seems to be a test, I see a green "secure" label in the Microsoft Bing search results for search results that are over HTTPS. I don't believe even Google ever tested a secure label in the search results, although Google does have an HTTPS ranking boost.
Here is a screen shot:
I was tipped off on this by Frank Sandtmann, someone who sends me a lot of Bing related changes. He also saw this being tested with a gray colored "secure" label.
I asked around if others are seeing the label, and some are not, some are seeing it in gray as well:
— Mayank Parmar (@mayank_jee) November 20, 2020
I see but mine are a bit different pic.twitter.com/lTm5KcANKV
— Pedro Dias (@pedrodias) November 20, 2020
I can see, but with little variations in visuals on Chrome and Edge. pic.twitter.com/Sq1OxPIAA5
— Praveen Sharma (@MusingPraveen) November 20, 2020
Not sure I like the "secure" label in the search results but it is a fun test.
Forum discussion at Twitter.