Letter highlighted by a dark font

I'm having this issue with Google's search box where last letters get highlighted with dark color as I'm writing something. This makes it annoying to spot typo errors while writing. I believe I pressed cmd/option key and something else, which caused this, maybe I changed some setting unknowingly, does anybody know how to change it back?

On Google's landing page search box the problem however does not persist, this is how it used to be on the beforementioned search box before: