Perhaps it's not the biggest factor, but it is likely to reduce employee benefits like education stipends, relocation stipends and dependent care FSAs.
Now that these benefits are much more expensive, you can except these benefits to reduced or eliminated, and the remaining costs to be take from your future salary.
Previously, employers were able to deduct the costs of these benefits from their tax bill, saving them money. The new tax plan eliminates these benefits (https://www.shrm.org/resourcesandtools/hr-topics/benefits/pa...).
Now that these benefits are much more expensive, you can except these benefits to reduced or eliminated, and the remaining costs to be take from your future salary.