You can easily override unwanted highlighting by switching the column type to Rich Text. When text is inserted from a Rich Text column, none of the formatting from the matched text is inherited, so the formatting of the inserted text is exactly as it is in your turnsheet.

While it's normally better to use Rich Text columns to insert formatted text, there may be cases where you need to insert formatted text in plain Text columns. If you want to clear any default formatting inherited from the matched text, use the Power-up 'Remove all formating' and surround the text you're inserting with ||.