Thank you. That is very helpful. I suggest you might start by using Malwarebytes to see if it will identify and remove them. If it cannot, then see the following:
The problem is not an extension but search hijacker. Try the following instructions I found: Search Marquis Virus Removal. Removing Search Baron is more complex, so here is a link to removal instructions: Remove Search Baron virus from Mac [Jun 2020] - MacSecurity. The instructions are after all the introductory material.
Step 1: Closing Safari (or any other browser that you may be using at the moment)
First, you will need to close your browser if it is still open. If you can’t do that normally, you will need to Force Quit it:
Open the Apple Menu and select Force Quit to do that. You can also use the ⌘ key + Option Key combination to open the Force Quit Applications dialog box. In this box, select the Safari browser (or whatever browser you are using) and then click on the Quit button. Confirm the action by selecting Force Quit again.
Step 2: Killing suspicious processes
Open Finder and go to Applications > Utilities and then open Activity Monitor. Now take a careful look at the processes there – look for any that seem suspicious, unknown and questionable. If you think that a given process may be the culprit behind the issue or may at least be related to it, highlight it with the mouse and select the i option at its top.
In the box that opens, click on Sample.
Scan the sample files with the online scanner we have on this page and if any of them get flagged as malicious, delete them and then kill their processes.
Step 3: Safely launching the browser
Hold the Shift from your keyboard and then launch Safari – holding Shift will prevent any previously opened pages to load again, just in case any of them were related to the problem.
If any problematic pages still load after you safe-launch the browser, then do the following:
Force-Quit the browser (Safari) again and then turn off your Wi-Fi connection by clicking on the Wi-Fi off option from the Mac Menu. If you are using cable Internet, simply disconnect the cable from your Mac.
Step 4: Uninstalling suspicious extensions
After you safe-launch Safari and are sure none of the previously opened pages load now, go to Preferences > Extensions.
Select and uninstall (by clicking on the Uninstall button) all extensions there that are unfamiliar to you or that you think may be suspicious. If you are not sure about a certain extension, it’s better to uninstall it – no extension is required for the normal functioning of the browser.
Step 5: Cleaning Safari
If you have other browsers aside from Safari, do the following:
In Safari, open Preferences from the browser’s menu and go to Privacy.
Select Remove All Website Data and then Remove Now. Note that this will delete all stored site data including any saved passwords and usernames. In other words, you will have to manually log-in to every site where you have a registration so make sure you remember your usernames and passwords.
Back in Preferences, click on General and see what your Safari’s homepage is. If it has been changed without your permission, change it back to what it used to be or to whatever you like it to be now.
Now go to the History menu and select the Clear History option.
