Highlighting can still apply when a query contains typos.
If you want to prevent typo matches from appearing at all, you can turn off typo tolerance. Keep in mind this can reduce the number of matches returned.
If you’re building a custom UI, you can enable getRankingInfo and use _rankingInfo.nbTypos to inspect the typo count for each hit. You can then choose how to render those results in your interface, such as only applying custom highlighting when nbTypos is 0.