Stop safari from opening all links in new tabs

All of a sudden, without making any changes to my safari settings, all links I press in safari opens the website in a new tab... This has been the case for a while, and started appearing after upgrading to OS X Mojave.

To further explain - if I search for "Apple" in the search bar in safari, it lists the results in Google as normally. Though when I click on one of the listed search results, the website opens in a new tab instead of simply showing the website in my current tab (which is what usually only happens if you "command+click" the website.

The same happens if I find myself in one of the opened websites and press a link within that website - and safari opens yet another tab

This means that I can sometimes end up having many tabs open from the same Google search as opposed to only have one tab open through which I can move back and forth from the different pages.

How do I turn this off and have it reversed back to normal?