Google tracking across search engines?

I had an open tab with my default search engine duckduckgo.
I couldn’t find what I wanted so I opened a second tab, typed, and typed my search on google.
When the results loaded, all the links I had opened on my duckduckgo tab were greyed out in the google tab, exactly as if google knew I had already opened them, in another tab and in another search engine.
Is this a normal behaviour?
(My browser clears cookies, cache and everything after each session, and it was the first time I opened a google tab in months).

It’s not Google that grayed them out but the browser. The links you already visited show a different color than those you didn’t, in all websites, unless the website has a C.S.S. that changes the browser’s settings regarding U.R.L. colors.

For extra security, what I do when I have to use Google is open a private window and load Google there. I also open any links I find on Google in that window. If I need those websites, I just copy and paste them in my regular window.

Google is very sneaky so keep on your toes.