Web of Trust is a popular extension, one we ourselves have recommended in the past. Unfortunately, that trust was misplaced -- the add-on has been removed from Chrome and Firefox's online repositories after it was alleged the creators were selling user data.
So, no big "this was doing bad stuff" notices from Google or Mozilla, however, the latter did make a comment:
The German newspaper FAZ managed to get a statement from Mozilla about the removal. According to the statement, Web of Trust was pulled because it violated add-on guidelines, and specifically transparency in regards to the add-on's collection of user data.
While browsers have a fair chunk of in-built security and Google and Firefox act as guardians (of a sort), we still have to put some faith in extension creators to do the right thing. It's really disappointing when that faith is betrayed.