I think it’s just the way the Obsidian markdown parser works. You might type a ( after the ] to make a markdown link, so it’s ready for ya! 
Some people don’t like that the color changes, and you can change it with a CSS snippet if it bothers you. I usually use single brackets for options to decide on later, so being different from the main text is good for me.
My work experience [was/turned out to be/ended up being] helping to pack for the mid-winter airdrop to Antarctica.