How to fix Safari redirection to yahoo search engine?

1. Try Safari Menu->Preferences->Search, and make sure its set to whatever Search Engine you want to use.
   1. Test. If it still doesn't work continue below.
2. Try downloading Malwarebytes and running it once, see if it finds anything and can remove it: link->>http://malwarebytes.com/mac/
   1. Test again. If it still does not work, continue below.
3. Download and run Etrecheck. Its a diagnostic utility, and post the results here so we may take a look. Link-> Using EtreCheck - Apple Community

I partially agree with you, but the system should be smart enough to remove something like this and not let the site or cookies make changes in search system on an app like Safari.

I personally did not install anything, but I have this problem.

It's not cookies or a website. It's the actual download and installation of something that made the change. Apple has no way of knowing that a change made by something you installed, is not the desired result.

Websites or cookies cannot alter system settings like that.

It happens due to your browser hijacked by some potentially unwanted program. They arrive in various forms like extensions, plug-ins, toolbars, search engines like Chillsearch[.]xyz that manages to change the default search preferences.

So, precisely its not a virus, but the actual reason being is a browser hijacker taking control over the browser. Eventually managing the search preferences that leads to the redirection. So, no matter how many times to try to revert back the settings, it will again stick to Yahoo on your Safari. Here I Found a fix for Stop Safari From Automatically Redirecting To Yahoo.https://techgeekspace.com/how-to-stop-safari-from-automatically-redirecting-to-yahoo/

Click here and run the tool.

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Unfortunately, this problem appeared after the last update in December. I think that Apple should solve this problem without the user resorting to other applications.

It's a Malware issue as has been made clear by Malwarebytes resolving it. Not something Apple can fix since its the download or installation of some app that caused it.