One of the most important revelations in Star Wars: The Last Jedi is that the First Order could track the Resistance through hyperspace. It shocked both the characters and the viewers, as this wasn't an ability explored prior to this installment. Not only that, but it gave the First Order a massive leg up on the Resistance, as they were no longer able to flee through hyperspace like ships were in the original trilogy.
Source：https://www.cbr.com/star-wars-last-jedi-hyperspace-tracking-rebels-hint/
