You have broken Search. The URLs for some search results are malformed, to the extent that you declare that
"Your browser sent a request that this server could not understand."

My browser didn't do anything other than try to follow the URL you provided. Since you and Mozilla conspire to hide the truth from me, I can't be sure what the problem is: When I mouse over the link, the URL displayed in the tooltip looks OK. When I "copy link", I get
https://r.search.yahoo.com/_ylt=AwrNY2zuEopqUwIAaUZXNyoA;_ylu=Y29sbwNiZjEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1788643310/RO=10/RU=https%3a%2f%2ftrending.knowyourmeme.com%2feditorials%2fcollections%2f14-of-the-dumbest-questions-ever-asked-on-yahoo-answers/RK=2/RS=QxqzsZL0TmbYnIoLi62OXo8qxWU-
which has been URL-encoded, making it harder for me to try the actual link, without all the tracking **** you insist on adding.

I have tried with and without Javascript. I have tried "private browsing", so no cookies. It started last night (Friday, 21 August 2026). It happened minutes after I successfully viewed a search result. On the other hand, even now I occasionally find a link that works, so, who knows, maybe you broke it a lot longer ago than last night while I was sitting here.

Assuming a human ever reads this, and actually cares, you could start by checking your statistics for how many "400 Bad Request" responses you are generating, and how that compares to history. I don't imagine anything other than using a Yahoo Search result is accessing r.search.yahoo.com.

I have tried Firefox, Chrome, Edge, and Opera. All fail.