Do you have a source for the claim that DuckDuckGo browser is selling user data to Microsoft?

You might be referring to the time when the DuckDuckGo browser was blocking all known trackers except Microsoft trackers. After that information was made public and users complained, DuckDuckGo was able to renegotiate its agreement with Microsoft so that it can block their trackers.

Furthermore, DuckDuckGo now publish their blocklist on GitHub.

Source: https://techcrunch.com/2022/08/05/duckduckgo-microsoft-tracking-scripts

So this privacy issue has been rectified now. But even if it hadn’t, failing to block Microsoft trackers isn’t the same as collecting data and selling it to Microsoft.

But if you are aware of DDG browser selling data to Microsoft, please share a source.

Really? I thought that used Bing search as backend but not that they sell your data