When you block third-party cookies then it makes not much sense to use AdGuard stealt mode, so I agee with
@Gandalf_The_Grey .
Adguard's trick to set an explicit expiration date on every third-party cookie (similar to exploding cookies) was an elegant way to circumvent website breakage and limit your tracks. Chrome announced the depreciation of third-party cookies, most advertising services started to provide alternatives. So less websites depend on third-party cookies to function, This is why Gandalf has to set exceptions for only a few websites.
I doubt that the referer information is blocked (it is in the header, not a param) and I am also unsure about the search search words are bing filtered in AG URL param filter (I thought they covered only advertising and campaign tracking stuff, not actual data being parsed in the URL)