Microsoft Bing Video search results has had a playlist feature since at least 2020. But now it seems Microsoft is testing displaying the playlist icon in the Bing web search results, not just the video results.
Khushal Bherwani spotted this and posted the following screenshots on Twitter showing the playlist icon showing in the Bing Web results on the right side panel.
Here is the icon on the right:
Here is what it looks like when it is open: