Remove light color highlight for copy-paste from the internet

Hello everyone

The topic has probably been raised several times, but I still haven't found the solution, so I'm reaching out to you. As part of my thesis, I need to translate texts, but when I copy texts from the internet, a subtle highlight (sometimes gray or pink) gets inserted, and I can't remove it since when I change the highlight to "no color" in Word, nothing changes.

Thank you for your valuable help.