Chill tab extension

   1. Remove unknown profiles if present.

      System Preferences > Profiles

      Open System Preferences, click the “Profiles” icon ( a checkmark on a gear) .

      When Profiles pane opens, select the unknown profile and click the minus button at the bottom.

  2. Remove unknown extensions:  Safari > Preferences > Extensions

      https://support.apple.com/guide/safari/use-safari-extensions-sfri32508/mac

   3. Check for adware.

       Run the latest release of Malwarebytes for Mac to remove malware/adware, if installed on your Mac.

       For instructions:  Install Malwarebytes for Mac          Uninstall Malwarebytes for Mac

       Click the “Scan Now” button. Once done, quit Malwarebytes for Mac.

       Restart the computer and relaunch Safari holding the shift key down.

       Scan for Malware again.

       Additional steps if necessary.

  4. Reset search engine:    https://support.apple.com/guide/safari/customize-your-search-ibrwe75c2a3c/mac

  5. Reset  Homepage.   https://support.apple.com/guide/safari/set-your-homepage-ibrw1020/mac 

  6. Restart your Mac. Relaunch Safari holding the Shift key down.      

You are welcome. That is a possibility. I would start by trying Malwarebytes as suggested by dominic.

 If necessary, follow the manual instructions. Please do not download any other programs that are listed in the articles.  

 Chill tab uninstall

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