Fabrice Canel from Microsoft Bing announced on the Bing blog that the search company will retire the legacy BingBot user-agent in the Fall of 2022. Instead, Bing will use a user-agent that is more representative of its evergreen BingBot rendering engine. Bing announced the new user agents back in 2019 but I guess this now means the old one is going away for good.
So out with this user-agent by the Fall of 2022:
Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)
In with these two new user-agents by the Fall of 2022:
Desktop:
Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm) Chrome/W.X.Y.Z Safari/537.36
Mobile:
Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/W.X.Y.Z Mobile Safari/537.36 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)
The “W.X.Y.Z” in the strings above, would be substituted with the latest Microsoft Edge version Bing is using for crawling, such as “100.0.4896.127″.
If you hard code anything for user-agents, you should update those details.
As an FYI, Google did the same thing with Googlebot user agents a couple years ago.
Forum discussion at Twitter.